How It Works Extreme Weather

EXCLUSIVE
MICHAEL FISH

INTERVIEW

UNCOVER
EARTH’S MOST
DESTRUCTIVE

FORCES

BOOK OF

AND THE SCIENCE BEHIND EARTH’S FORCES OF NATURE

V EXTREME CLIMATES V HEATWAVES V TORNADOES V SOLAR STORMS



WELCOME TO

BOOK OF

It’s part of human nature to discuss the weather on a daily
basis, but beyond a slight drizzle or chill in the air, what do we
know about the wildest weather to hit planet Earth? Extreme
weather events like lightning strikes, hurricanes, monsoons
and floods affect people around the world every day, so it is

important to understand the science behind them to avoid
death and destruction. This book looks at the most destructive
natural phenomena, their impact on the environment and how
humankind attempts to predict and control it. We even speak
to Michael Fish about his career at the UK Met Office and that
fateful storm of 1987. So take a look at the extraordinary sights

to behold on Earth (and beyond)!



BOOK OF

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How It Works Book Of Extreme Weather Second Edition © 2016 Imagine Publishing Ltd
ISBN 9781785462351

Part of the

bookazine series

How It Works Book Of Extreme Weather

Extreme weather 146 74

008 Extreme weather 131

Discover Earth’s most deadly weather Science of weather

016 50 strange facts about weather 100 Weirdest weather

Deadly weather What’s behind Earth’s weird weather?

026 Surviving extreme Earth 110 How the seasons work
112 How the Arctic Ocean freezes
Discover how to survive worldwide 114 The carbon cycle
116 How does wind erosion work?
036 Cyclone vs anticyclone 117 Atmospheric temperature
038 Megafloods 117 Clouds that shine at night
042 Drought 118 Mammatus clouds
043 Hurricanes and typhoons 118 How is dew formed?
044 Lightning
048 Heatwaves
050 Rise of the superstorm
054 Firestorms
058 Monsoons
059 Avalanche!
060 Killer storms

Forces of nature

066 Earth’s extreme climates

Explore the different Earth climes

070 How do jet streams work?
072 La Nina
073 The science of wind
074 Supercell thunderstorms
076 Where does acid rain come from?
077 Hailstones
078 How do insects survive floods?

Space weather

082 Wildest weather in space

Understand space’s deadliest storms

086 What is space weather?
087 Why is Venus so hot?
087 Solar tsunamis
088 Amazing Martian weather
089 Weather on Jupiter
090 Deadly solar storms
094 Solar tornadoes
096 Extreme space temperatures

006

54

119 © Corbis

90 © OliverSpalt The weather & us
121
© Christian Thiergan 138 Controlling the weather

119 What are Von Kármán vortices? 50 Find out how we can control it
120 How do waterfalls freeze?
121 Why do we get red sky at night? 142 Wind tunnels
121 What is wind-chill factor? 143 Measuring wind speed
121 The smell of rain 143 Sunblock
122 Cave weather 144 Predicting the weather
124 The ozone layer explained 146 Weather forecaster Michael Fish
125 Antarctica’s ozone hole 148 Renewable and non-renewable
126 Cloud-spotting guide
127 Why are clouds white? energy
127 Rain shadows 150 Solar power
128 Why, and how, does it rain? 154 Ivanpah Solar Power Facility
128 What are fog, mist and haze? 156 Power from the oceans
129 Double rainbows 158 How flood barriers work
130 Why is snow white?
131 What are lenticular clouds? 007
131 Aurora borealis
132 Nitrogen cycle
134 Influencing cloud formation
135 Snowflakes
135 Weather symbols

EXTREME WEATHER

Weather extremes

Uncovering the origins of the most savage meteorological
phenomena that the world has ever seen

‘A butterfly flaps its wings in China and a hurricane downed around 15 million trees, caused nearly £5 billion
hits Florida’ – or at least so goes the well-known ($8 billion) worth of damage and forced the National Grid to
saying. That’s usually a metaphorical expression shut down the power supply to London.
that describes the Butterfly Effect, the idea that the
sequence of events which leads to an eventual outcome is so As a force 11/12 storm on the Beaufort scale at worst, the
chaotic and so far removed from its source that it’s near Great Storm of 1987 would be the equivalent of a category 1
impossible to determine. In the case of predicting the hurricane or a severe tropical storm. It’s weather that
weather, however, it can be taken literally. Although subequatorial regions are well used to, if not prepared for,
meteorologists might not be quite at the stage of pinning a but which is unheard of in more temperate climes. The
specific weather pattern down to the movements of an fortunate thing about these freak occurrences is that, more
insect, they have got the science of weather prediction often than not, they can be traced to a source. So even if we
down to a fine art. But they do get it wrong sometimes. can’t do anything to stop it happening again, scientists are
In mid-October 1987, UK meteorologists predicted a spot more informed of the signs of extreme weather and perhaps
of bad weather would hit the south coast of Britain but the we can be more prepared the next time a mega-storm hits.
deepening depression over the continent would progress no
further than the English Channel. As it turned out, the In this eight-page feature, we delve into some of the most
depression not only moved on to the UK mainland, but also extreme examples of weather from across the globe, what
plummeted to a low of 953 millibars at the centre of what makes them so weird, the meteorological records they
would later be christened the ‘Great Storm of 1987’. Indeed, broke, the damage they caused, as well as the human cost.
it was the worst tempest to hit northern Europe in nearly Where did the freak storms come from? What conditions
300 years, with winds gusting up to 196 kilometres (122 gave rise to those temperatures and will anyone ever see
miles) per hour in the UK and even faster in France. It rain like that again? Trace the floods, droughts, winds,
rains and more back to their source to find out exactly what
took them to a whole other level.

008

“The Phoenix haboob included heavy
metal pollutants, fungi and bacteria
that could cause eye infections”

Phoenix Sudan sees a lot of The Phoenix haboob
USA haboobs – in fact, it is
where the name originates Where: Phoenix, USA When: 18 August 2011
Cool fact Fatalities: 3 Weather type: Dust storm
What you see here isn’t a cloud or smoke from a fire , but a haboob:
They may just be a dust storm of monumental proportions that hit Phoenix,
dust, but haboobs Arizona, in August 2011. Although the dust storms themselves
can take down power aren’t especially unusual in the region, this was a monster at two
lines, jam electrical kilometres (1.2 miles) high and 100 kilometres (62 miles) across.
devices and play
havoc with aircraft. Early June marks the beginning of the monsoon season for
Arizona and it’s where this massive haboob began its life. Most of
the land was still very dry when a large thunderstorm-forming
depression settled over the desert, causing winds to move into its
centre. When it collapsed, the winds reversed and downdraughts
of up to 100 kilometres (62 miles) per hour blew across the arid
region, kicking up a huge wall of dust that swept over the city.

Haboobs occur in several desert areas, including the Middle
East and Australia. They’re not particularly dangerous, but the
dust gets everywhere and they can leave a covering of up to 0.3
metres (one foot) of sand. The Phoenix haboob included additional
hazards in the form of heavy metal pollutants, fungi and bacteria
that could cause eye infections and lung diseases.

Cumulonimbus

Cold downdraughts

Gust front

© Getty

009

EXTREME WEATHER

Weather extremes

Australian fire devil

Where: Alice Springs, Australia When: 16 September 2012

Fatalities: 0 Weather type: Fire devil

They’re more akin to dust devils

Alice Springs than tornadoes, but the flaming
columns that form fire devils are

Australia much rarer than either. They’re
hardly ever seen and rarely last

long, which makes this most

recent event in the Australian

outback so much more incredible.

Filmmaker Chris Tangey had been working in the Alice

Springs area when he was confronted with this 30-metre

(100-foot) pillar of flame. Not only did it ‘sound like a fighter

jet’, but it lasted nearly 40 minutes, giving Tangey ample

time to video it and take photographs.

Fire devils can occur when a column of warm air forcing

its way up either comes in contact with a fire or conditions Cool fact

are right for it to create a spark. In the case of this fire Fire devils have been

devil, a bush fire that had raged for a week, plus an seen reaching as

extended dry spell since April 2012, along with a perfectly high as 1km (0.6mi)

into the air.

still day were ripe conditions for the fire tornado.

The North American Canada Montréal

Ice Storm of 1998 USA

Where: North-east America When: 7 January 1998 Fatalities: 55
Weather type: Ice storm Damage: $6 billion (£3.7 billion)

Ice storms are common on the east coast of the US and

Canada. The infrastructure is generally prepared for the

havoc these storms can wreak, but winter 1998 brought with

it the most crippling ice storm in living memory.

By 5 January 1998 it was clear eastern North America was

in for a cold spell. An area of unusually high pressure was

sitting over the Atlantic, trapping several weather systems

on the land. Arctic air was being held at the surface in this

area, while a front of low pressure was feeding it with warm,

moist air from the Gulf of 1. Moist air is forced 2. Snow falls through
Mexico. The result was upwards and forms the warm middle layer
12.7 centimetres (five snow at high altitude.
inches) of freezing rain and melts into small
that fell over 80 hours, water droplets.
crystallising on anything
Cold

it touched, taking down Deep
power lines, felling trees warm
and making roads 3. The droplets fall into layer
impassable everywhere. a very cold surface layer
One of the worst-hit cities of air and supercool,
was Montréal in Québec. forming freezing rain.
Cold

010

“The River Thames in London
totally froze over for two months”

The Tri-State Tornado

Where: Southern USA When: 18 March 1925 Fatalities: 695 (confirmed)
Weather type: F5 tornado Damage: $16.5m ($1.4bn/£873m today)

The deadliest tornado in US ground-hugging cloud, rather than Missouri
history was part of a tornado the characteristic funnel shape. USA
outbreak that struck the southern
states in spring 1925. It touched The Tri-State Tornado was born
down in Missouri and tracked out of a cold low-pressure system
north-east through Illinois and on that had been following what we
to Indiana where it dissipated. In now know is the jet stream, down
its wake the F5 monster – the from Canada, along the Texas-
highest possible rating on the Oklahoma border and into
Fujita scale – destroyed 15,000 Missouri. It’s here that it hit a
homes and killed hundreds of warm front from the Gulf of Mexico
people. It could move at 110 and conditions were made perfect
kilometres (70 miles) per hour, for a tornado outbreak. Judging by
travelled 352 kilometres (219 miles) the speed the Tri-State Tornado
and, because it was so massive, it travelled at, it’s likely the winds in
appeared as an enormous black, the jet stream were particularly
strong at the time.

The Little Ice Age 1931 Yellow River flood

Northern Europe Where: Northern Europe When: 1350-1850 Where: China When: July-November 1931 Fatalities: Up to 4 million
London Damage: N/A Weather type: Global cooling Weather type: Flood Damage: Unknown billions

In 1931, China experienced one of the

France deadliest natural disasters ever. Having had
Yellow River a two-year drought, China’s three big rivers

China burst their banks over three months: the

overflowing Yangtze and Huai drowned

nearly half a million people between them,

but casualty estimates of the Yellow River

flood are as high as 2 million. Millions more

faced starvation and sickness from waterborne diseases like cholera.

Both the human and financial costs are hard to calculate. No single

factor can be blamed for this tragic event, but it’s believed that large

The ‘Little Ice Age’ wasn’t a true winter of 1683-1684, the River amounts of meltwater from a particularly snowy winter, combined
ice age, but a period of Thames in London completely
significant cooling that took froze over for two months and in with heavy spring rain, began the
place worldwide (though it was Switzerland entire villages were
felt most keenly in northern lost to advancing glaciers. abnormal flooding season. This was
Europe) over the course of 500
years. It was punctuated by Evidence suggests that this followed by no less than seven torrential
several brief warming periods period of global cooling could
with the coldest period have been caused by a number typhoons in July alone, when China
manifesting itself in the of factors combined. Volcanic
late-17th and early-18th activity around Indonesia in the usually only sees two in a whole year.
centuries. It’s during the 13th century had a likely
winters over this period that the long-term effect, while a very Cool fact These days, Yellow River © NOAA; SWNS; Corbis
European landscape completely slight shift in the Earth’s orbit at flood relief comes in the
changed to something evocative this time definitely contributed. The Yellow River has
of what might happen if a real The dips in this cooling period several dams, which form of a controlled
ice age occurred. Over the bitter also coincided with minimums have been broken in burst from the
in solar activity. the past to use the Xiaolangdi Dam
river as a weapon
against enemy armies.

011

EXTREME WEATHER Cool fact St Louis

Weather extremes Tornadoes can (and Wichita
have) formed in the USA
I-44 Tornado UK, though the great
Corridor plains of America are
the perfect breeding
Where: Oklahoma, USA Weather type: Tornadoes ground for them.
There are several regions of the world where
tornadoes have a tendency to touch down on a Windy & cooler
regular basis, but the 177-kilometre (110-mile) Steamy
strip of land that runs from Oklahoma City to
Tulsa is one of the most notorious. It follows part Maracaibo
of the St Louis to Wichita Falls Interstate 44
(hence the name) and has seen hundreds of Venezuela
destructive tornadoes tear down its length in the Colombia
last century. The worst of these have ploughed a
strip straight through Oklahoma City itself and,
on 3 May 1999, no less than 70 touched down in
the region. One of these was a devastating F5 on
the Fujita scale that killed 40 people, left
thousands homeless and caused
$1 billion (£620 million) of damage.

Conditions at spring time make the I-44
corridor ripe for tornadoes: as warm, moist air
drifts north from the Gulf of Mexico across the
southern states, it’s met by cool, dry air moving
high off the tops of the Rocky Mountains to the
west. Combined with the huge, flat expanses of
land in the region, it’s perfect for twisters.

Lighthouse of
Maracaibo

Where: Lake Maracaibo, Venezuela
Weather type: Lightning
There’s a lightning storm over Lake
Maracaibo that has raged on and off for
centuries. This unique phenomenon can be
seen from many miles away, illuminating
the lake and its surroundings for up to 160
nights a year. Recent data from the
University of Zulia showed the Maracaibo
Lake basin to have the hottest flash density
rate in the world, with an annual average of
181 lightning flashes per square kilometre.
Indeed, during peak months, there can be 50
discharges every minute! The Lighthouse of
Maracaibo is caused by very specific
conditions. The wind that blows in across
the plains is trapped by the surrounding
Andes and Perijá mountains, along with the
warm, moist air it collected from the plains.
The swampy land in this region produces a
lot of methane, which rises into the charged
clouds and is the catalyst for near-
continuous lightning.

012

The storms of Airborne
invaders
Drake Passage
Australian Dust Storm
Where: South Atlantic/Pacific
Weather type: Sea storm 2009 saw a dust storm of
enormous proportions engulf
It’s known as the the Australian territories of
New South Wales and
Argentina roughest patch of ocean Queensland. It was nearly
3,500 kilometres (2,175 miles)
in the world ever since long at its peak.
Atlantic English privateer and Meteorologists suspect that a
low-pressure front and
Drake Passage explorer Sir Francis 100-kilometre (62-mile)-per-
Drake gave it his name in hour winds picked up dust
from the dry interior and
1578. Drake Passage is a carried it to the coast.

stretch of water 800 kilometres (500 miles) wide Réunion Island rains

from the southern tip of South America to the The island of Réunion, east of
Madagascar, boasts seven of
frosty islands that surround Antarctica. the world’s top ten rainfall
records, including: 182.4
These seas are rarely anything less than centimetres (71.8 inches) in 24
hours and 5.7 metres (18.63
choppy and are frequently challenging even feet) in ten days.

the most seasoned navigators and sailors. The Meschera money storm

wind in alternate passages from the southern In the summer of 1940, a
shower of 1,000 or so 16th-
Cool fact Atlantic into the Southern or Pacific Oceans is century silver coins
reportedly dropped on the
Continental drift often too strong to make any headway against, Meschera region of Russia
opened Drake during a violent storm. It’s
Passage 41 million so Drake Passage is usually chosen as the lesser suspected that the coins were
years ago, creating from a buried treasure hoard
the Antarctic of two evils despite its treacherous waters. that was ripped out of the
Circumpolar Current ground, perhaps by a falling
which helps to keep The Antarctic Circumpolar Current that tree, and carried up by high
the continent cold. winds before being dropped.
travels swiftly through Drake Passage is made
1972 Iran Blizzard
rough by the high winds that move from west to
Freezing temperatures and
east at this latitude, creating waves that are storms in southern Iran
resulted in up to eight metres
frequently ten metres (32 feet) or higher. (26 feet) of snow blanketing
more exposed areas, killing
The Creeping Minqin County 4,000 people and burying © Corbis; Getty; Daniella Dearden; Mrcricket48; NASA, Wiki
Sandbox China several villages entirely.

Where: Gansu province, China “In just over 50 years, 013
Weather type: Sand storm more than 259km2
To most of us, a desert is an arid region that is (100mi2) have succumbed
relatively fixed. We don’t think of them as to desertification”
growing entities that can overwhelm
communities in our lifetime, but that’s exactly
what’s happening to the once fertile Minqin
Oasis region of China.

This farming community is being rapidly
evicted by two deserts that sandwich it: the
Tengger to the south-east and Badain Jaran to
the north-west. In just over 50 years, more than
259 square kilometres (100 square miles) have
succumbed to desertification by the sands that
advance at ten metres (32 feet) a year. While
arable land has decreased from 932 to 155 square
kilometres (360 to 60 square miles), the
population has more than doubled, so farmers
constantly need to relocate. Part of the reason
Minqin is being swallowed up so fast is a
long-term drought in the area and because the
oasis’s life source – the Shiyang River – has been
diverted farther upstream.

EXTREME WEATHER

Weather extremes

Cyclones, typhoons Hurricane Katrina
and hurricanes Where: New Orleans, USA When: August 2005
Fatalities: 1,833 Damage: $108bn (£670m)

One of the deadliest hurricanes in recent memory and

Devastating wind storms come with many the most destructive in US history, Hurricane Katrina
names, but do they differ in any way? profoundly affected New Orleans and its surroundings,
where water reached up to 20 kilometres (12 miles)

What’s the difference between a cyclone, a from the shore. Hurricane Katrina was the child of a
typhoon and a hurricane? In fact, there is none. waning tropical depression and an atmospheric trough
These are the regional names given to a certain known as a tropical wave. It moved across the Gulf of
type of violent storm. So, cyclones occur in the Mexico and rapidly strengthened over unseasonably
south Pacific and Indian Ocean, typhoons in warm waters, transforming into a maximum-rated
the north-west Pacific, while in the Atlantic or category 5 hurricane and shifting away from Florida
north-east Pacific they’re called hurricanes. shortly before it slammed into the vulnerable city of
New Orleans in south-east Louisiana.
These violent storms are characterised by

extremely strong winds that can gust in excess

of 200 kilometres (125 miles) per hour,

torrential rain, floods and extremely high seas.

At the centre of these storms is an ‘eye’, a

circular region typically between 30 and 65

kilometres (20 and 40 miles) wide that moves

with the storm and marks the low point of the

atmospheric depression. The eye itself is cold, Cool fact
deceptively calm and sunny, though the
strongest winds and thunderstorms encircle its Wind and rain were
border, forming the eyewall. so strong when the
Great Hurricane hit
The ingredients for a storm of this type Barbados that it’s
include an existing weather system combined reported bark was
with warm seas, which is why they only ever stripped from trees!

occur in subequatorial latitudes. These storms

don’t form within 500 kilometres (300 miles) of Equator
the equator because they rely on the swirling

Coriolis effect for its rotation, which diminishes

to zero the closer you are to the equator. With

rare exceptions, neither do they form in waters

with a surface temperature colder than around The Great Hurricane Bhola Cyclone
26 degrees Celsius (80 degrees Fahrenheit), of 1780
which rules out much of the rest of the world. Where: Bangladesh When: November 1970
Where: Caribbean When: October 1780 Fatalities: 500,000 Damage: $490m (£306m)
As with many types of extreme weather, the Fatalities: 22,000 Damage: Unknown
size and intensity don’t necessarily reflect its The Bhola Cyclone was, meteorologically
notoriety: the typhoon, for example, is Simply known in English as the Great speaking, far from record-breaking. Its winds
typically several times bigger than its Atlantic Hurricane of 1780, this category 5 beast is of around 140 kilometres (87 miles) per hour
cousin, the hurricane. But many smaller the deadliest hurricane on record. It made it the equivalent of a relatively modest
hurricanes have achieved a higher profile predates when records officially began in category 3 or 4 hurricane. But it struck a very
simply because they made landfall and 1851, so there’s no exact data. It’s likely
devastated the highly populated southern though that its wind speed exceeded 320
states of the US. kilometres (200 miles) per hour and it

Key devastated the relatively unprepared parts vulnerable low-lying area of eastern Pakistan
of the Antilles in the Caribbean Sea. with a six-metre (20-foot) storm surge at night.

Cyclones, hurricanes and Hurricanes Casualties include fleets of British and With no way of warning locals, the authorities
typhoons form in the warm Cyclones French ships that were vying for control of were helpless as hundreds of thousands
waters near the equator from Typhoons the region as a part of the American drowned. Bhola formed from the remnants of
where they circulate away. Their Revolution. It’s likely it formed in the a tropical storm and another depression in the
general course is predictable, eastern part of the Atlantic Ocean picking Bay of Bengal, intensifying over four days and
though it’s hard to know what up strength as it approached Barbados. sweeping north into what is now Bangladesh.
they will do or how strong they
will get over longer periods.

014

Hurricane Vince Cool fact Super Typhoon Tip

Where: Portugal/Spain When: October 2005 Hurricane Vince Where: Eastern Pacific When: October 1979
Fatalities: 0 Damage: N/A proved to be a Fatalities: 86 Damage: Unknown
Its winds peaked at 120 kilometres (75 blessing in disguise, Super Typhoon Tip was a monster, even for
miles) per hour, which only just registers dropping several a typhoon. It broke several records: it had a
as an official hurricane, it caused no inches of rain on a diameter of 2,220 kilometres (1,380 miles)
damage and there were no fatalities, so drought-ridden Spain. – nearly twice that of the previous record
why could Hurricane Vince be considered holder. It had sustained winds of 260
‘extreme’? Because of its unheard-of kilometres (160 miles) per hour and also set
Spanish location and because of the world record for intensity with a
conditions at the time, which should never staggering pressure low of 870 millibars.
have produced a hurricane. The reasons Typhoon Tip originated south of
for its formation near Madeira still aren’t Micronesia though it remained a tropical
understood. The 22-degree-Celsius storm until it made a sudden westerly
(72-degree-Fahrenheit) seas should never diversion from Guam, where it intensified
have allowed the 25-kilometre (15-mile) eye considerably and hit its peak nearly 1,000
to form within the tropical storm. But form kilometres (620 miles) from land.
it did, and it lasted several hours, breaking
up just before it hit the Spanish mainland. Cool fact

Experts agree that
Typhoon Tip would
have been the most
disastrous ever if it
had hit the mainland
at peak intensity.

Cool fact © Corbis; NASA

Cyclone Tracy was,
until 2008, the
world’s smallest
cyclone with a width
of just 48km (30mi).

Cyclone Tracy

Where: Darwin, Australia When: 25 December
1974 Fatalities: 71 Damage: $586m (£366m)
On Christmas Day 1974, a category 4 cyclone
swept through Darwin, Australia, with winds
gusting in excess of 217 kilometres (135 miles)
per hour towing a four-metre (13-foot) storm
surge. Locals had been warned, but partly
due to the season and partly because Cyclone
Selma had failed to make landfall earlier that
month, many made no preparations at all.
Cyclone Tracy developed in the seas 500
kilometres (300 miles) north of Australia and
spent the next few days tracking south-east
until it hit the warm water of the Timor Sea,
where it intensified dramatically.

015

50 STRANGE WEATHER FACTS

Meteorological marvels

50

strange
facts about

We answer your burning questions about the
incredible variety and awesome power of the
planet’s most intriguing climatic phenomena

We like to be able to control everything, but weather Here’s what we do know: all weather starts with contrasts in
– those changes in the Earth’s atmosphere that spell air temperature and moisture in the atmosphere. Seems
out rain, snow, wind, heat, cold and more – is one of simple, right? Not exactly. Temperature and moisture vary
those things that is just beyond our power. Maybe that’s why a greatly depending on a huge number of factors, like the Earth’s
cloudless sunny day or a spectacular display of lightning both rotation, where you’re located, the angle at which the Sun is
have the ability to delight us. Meteorologists have come a long hitting it at any given time, your elevation, and your proximity
way in their capability to predict weather patterns, track to the ocean. These all lead to changes in atmospheric pressure.
changes and forecast what we can expect to see when we leave The atmosphere is chaotic, meaning that a very small, local
our homes each day. But they’re not always right. It’s not their change can have a far-reaching effect on much larger weather
fault; we still don’t completely understand all of the processes systems. That’s why it’s especially tough to make accurate
that contribute to changes in the weather. forecasts more than a few days in advance.

016

DID YOU KNOW? Many types of animals are reported to have fallen from the sky including frogs, worms and fish

Is there a way to tell 1. Start the count CAN IT
how close a storm is? REALLY RAIN
When you see a flash of lightning, ANIMALS?
Lightning and thunder always go together, because thunder is the sound that start counting. A stopwatch would
results from lightning. Lightning bolts are close to 30,000 degrees Celsius be the most accurate way. Animals have fallen
(54,000 degrees Fahrenheit), so the air in the atmosphere that they zip from the sky before,
through becomes superheated and quickly expands. That sound of expansion 2. Five seconds but it’s not actually
is called thunder, and on average it’s about 120 decibels (a chainsaw is 125, for ‘raining’ them. More likely
reference). Sometimes you can see lightning but not hear the thunder, but The rule is that for every five strong winds have picked up large
that’s only because the lightning is too far away for you to hear it. Because seconds, the storm is roughly 1.6 numbers of critters from ponds or
light travels faster than sound, you always see lightning before hearing it. kilometres (one mile) away. other concentrations – perhaps
from tornadoes or downspouts –
3. Do the maths then moved and deposited them.
Usually the animals in question
Stop counting after the thunder and are small and live in or around
do the maths. If the storm’s close, water for a reason.
take the necessary precautions.
DOES FREAK WEATHER
What is the fastest Is it possible to CONFUSE WILDLIFE?
wind ever recorded, stop a hurricane?
A short period of unseasonable
not in a tornado? We can’t control the weather… or weather isn’t confusing, but a
can we? Some scientists are trying longer one can be. For example,
407km/h (253mph) to influence the weather through warm weather in winter may
Gusts recorded during cloud seeding, or altering the clouds’ make plants bloom too early or
Cyclone Olivia in 1996 processes by introducing chemicals animals begin mating long before
like solid carbon dioxide (aka dry spring actually rolls around.
ice), calcium chloride and silver
iodide. It has been used to induce IS THE ‘RED SKY AT
rainfall during times of drought as NIGHT, SHEPHERD’S
well as to prevent storms. DELIGHT’ SAYING TRUE?

The rest of the proverb is, ‘Red sky
at morning, shepherd’s warning’.
A red sky means you could see the
red wavelength of sunlight
reflecting off clouds. At sunrise, it
was supposed to mean the clouds
were coming towards you so rain
might be on the way. If you saw
these clouds at sunset, the risk had
already passed. Which is ‘good’ or
‘bad’ is a matter of opinion.

WHAT ARE SNOW
DOUGHNUTS?

Snow doughnuts, or rollers, are a
rare natural phenomenon. If snow
falls in a clump, gravity can pull it
down over itself as it rolls.
Normally it would collapse, but
sometimes a hole forms. Wind and
temperature also play key roles.

What makes clouds? Cloud

Buildup Air currents rise up and
become thermals – rising
The warm, moist air builds
up somewhere between 305m columns of warm,
and 1,525m (1,000-5,000ft) expanding air.
above the surface.
Bases
Warm, wet
air rises The bottom of
the cloud is the
Sunlight heats and saturation point
evaporates water from of the air, and it
the Earth’s surface. is very uniform.

017

50 STRANGE WEATHER FACTS

Meteorological marvels

WHAT ARE What causes hurricanes?
KATABATIC
WINDS? Depending on where they start, hurricanes the storm is officially a hurricane. When Cool, dry air
may also be known as tropical cyclones or hurricanes reach land, they weaken and die
From the Greek for typhoons. They always form over oceans without the warm ocean air. Unfortunately Cooled, dry air at the top of the
‘going downhill’, a around the equator, fuelled by the warm, they can move far inland, bringing a vast system is sucked down in the
katabatic wind is also moist air. As that air rises and forms clouds, amount of rain and destructive winds. centre, strengthening the winds.
known as a drainage more warm, moist air moves into the area of People sometimes cite ‘the butterfly effect’ in
wind. It carries dense air lower pressure below. As the cycle continues, relation to hurricanes. This simply means Eye
down from high elevations, such winds begin rotating and pick up speed. something as small as the beat of a butterfly’s
as mountain tops, down a slope Once it hits 119 kilometres (74 miles) per hour, wing can cause big changes in the long term. High-pressure air flows
thanks to gravity. This is a downward through this
common occurrence in places calm, low-pressure area at
like Antarctica’s Polar Plateau,
where incredibly cold air on top of the heart of the storm.
the plateau sinks and flows down
through the rugged landscape, Winds
picking up speed as it goes. The
opposite of katabatic winds are As the warm, moist air
called anabatic, which are winds rises, it causes winds to
that blow up a steep slope. begin circulating.

DOES IT EVER SNOW How hot is Warm, moist air
IN AFRICA? lightning?
This air rises up from the
Several countries in Africa see 27,760˚C oceans, cooling on its way
snow – indeed, there are ski (50,000˚F) and condensing into clouds.
resorts in Morocco and regular
snowfall in Tunisia. Algeria and © SPL If the Moon didn’t exist it
South Africa also experience would have a catastrophic
snowfall on occasion. It once
snowed in the Sahara, but it was effect on world climates
gone within 30 minutes. There’s
even snowfall around the equator What would happen to our weather without the moon?
if you count the snow-topped
peaks of mountains. It’s difficult to know exactly what would happen to our addition it would alter the tilt of the Earth too, which causes
weather if the moon were destroyed. The Moon powers the changes in our seasons. Some places would be much
WHAT COLOUR Earth’s tides, which in turn influence our weather systems. colder while others would become much hotter. Let’s not
IS LIGHTNING? In addition, the loss of the moon would affect the Earth’s neglect the impact of the actual destruction, either; that
rotation – how it spins on its axis. The presence of the Moon much debris would block out the Sun and rain down on
Usually lightning is white, but creates a sort of drag, so its loss would probably speed up Earth, causing massive loss of life. Huge chunks that hit the
it can be every colour of the the rotation, changing the length of day and night. In ocean could cause great tidal waves, for instance.
rainbow. There are a lot of factors
that go into what shade the
lightning will appear, including
the amount of water vapour in the
atmosphere, whether it’s raining
and the amount of pollution in
the air. A high concentration of
ozone, for example, can make
lightning look blue.

WHY DO SOME CITIES
HAVE THEIR OWN
MICROCLIMATE?

Some large metropolises have
microclimates – that is, their own
small climates that differ from
the local environment. Often
these are due to the massive
amounts of concrete, asphalt and
steel; these materials retain and
reflect heat and do not absorb
water, which keeps a city warmer
at night. This phenomenon
specifically is often known as an
urban heat island. The extreme
energy usage in large cities may
also contribute to this.

018

RECORD DEADLIEST NATURAL DISASTER

3.7-4MNBREAKERS The Huang He flood of 1931 covered over 100,000 square
kilometres (62,000 square miles) around the Yellow River

KILLER FLOOD basin in China, claiming up to a staggering 4 million lives.

DID YOU KNOW? Sir Francis Beaufort devised his wind scale by using the flags and sails of his ship as measuring devices

How many WHAT IS
volts are in CLOUD
a lightning IRIDESCENCE?

flash? This happens when
small droplets of water
1 billion or ice crystals in clouds
scatter light, appearing as a
© SPL rainbow of colours. It’s not a
© SPL common phenomenon because
Why are you safer inside a car What causes the cloud has to be very thin, and
during an electrical storm? giant hailstones? even then the colours are often
overshadowed by the Sun.
People used to think the rubber tyres on a car grounded any Put simply, giant hailstones come from giant storms
lightning that may strike it and that’s what kept you safe. – specifically a thunderstorm called a supercell. It has WHAT DO WEATHER
However, you’re safer in your car during an electrical storm a strong updraft that forces wind upwards into the SATELLITES DO?
because of the metal frame. It serves as a conductor of clouds, which keeps ice particles suspended for a long
electricity, and channels the lightning away into the ground period. Within the storm are areas called growth The GOES (Geostationary
without impacting anything – or anyone – inside; this is known regions; raindrops spending a long time in these are Operational Environmental
as a Faraday cage. While it is potentially dangerous to use a able to grow into much bigger hailstones than normal. Satellite) system is run by the US
corded phone or other appliances during a storm because National Environmental Satellite,
lightning can travel along cables, mobile or cordless phones are Data, and Information Service
fine. It’s also best to avoid metallic objects, including golf clubs. (NESDIS). The major element of
GOES comprises four different
How does the Sun cause the seasons? geosynchronous satellites
(although there are other
Seasons are caused by the Earth’s revolution around the Sun, as Vernal equinox geo-satellites either with other
well as the tilt of the Earth on its axis. The hemisphere receiving uses now or decommissioned).
the most direct sunlight experiences spring and summer, For the northern
while the other experiences autumn and winter. During the hemisphere, this day – The whole system is used by
warmer months, the Sun is higher in the sky, stays above the around 20 March – marks NOAA’s National Weather Service
horizon for longer, and its rays are more direct. During the the first day of spring. On for forecasting, meteorological
cooler half, the Sun’s rays aren’t as strong and it’s lower in the this day, the tilt of the Earth’s research and storm tracking. The
sky. The tilt causes these dramatic differences, so while those axis is neither towards nor satellites provide continuous
in the northern hemisphere are wrapping up for snow, those in away from the Sun. views of Earth, giving data on air
the southern hemisphere may be sunbathing on the beach. moisture, temperature and cloud
cover. They also monitor solar and
near-space activities like solar
flares and geomagnetic storms.

Winter solstice

The winter solstice marks the
beginning of winter, with the

Sun at its lowest point in the
sky; it takes place around 20

December each year.

SUMMER WINTER

The Sun is at its highest point in The Sun is at its lowest point in the
the sky and takes up more of the sky and there is less daylight. The
horizon. Its rays are more direct. rays are also more diffuse.

Summer solstice Autumnal
equinox
During the summer solstice,
around 20 June, the Sun is at On, or around, 22
its highest, or northernmost, September in the
point in the sky. northern hemisphere,
this marks the start of
autumn. The tilt of the
Earth’s axis is neither
towards nor away

from the Sun.

019

50 STRANGE WEATHER FACTS

Meteorological marvels

HOW LONG What is the eye of a storm? What’s the
DOES A difference
RAINBOW The eye is the calm centre of a storm like a hurricane or tornado, between rain,
LAST? without any weather phenomena. Because these systems consist of sleet and snow?
circular, rotating winds, air is funnelled downward through the eye
There is no set rule for and feeds back into the storm itself. When it comes to precipitation, it’s
the duration a rainbow all about temperature. When the
will last. It all depends on air is sufficiently saturated, water
how long the light is refracted vapour begins to form clouds
by water droplets in the air (eg around ice, salt or other cloud seeds.
rain, or the spray from a waterfall). If saturation continues, water
It can range from moments to droplets grow and merge until
much longer. they become heavy enough to fall
as rain. Snow forms when the air is
WHY DOES IT SMELL cold enough to freeze supercooled
FUNNY AFTER RAIN? water droplets – lower than -31
degrees Celsius (-34 degrees
This scent comes from bacteria in Fahrenheit) – then falls. Sleet is
the soil. Once the earth dries, the somewhere in between: it starts
bacteria (called actinomycetes) as snow but passes through a
release spores. Rainfall kicks layer of warmer air before hitting
these spores up into the air, and the ground, resulting in some
then the moist air disperses snow melting.
them. They tend to have a sweet,
earthy odour. How high
is a typical
HOW MUCH RAIN CAN
A HURRICANE BRING? 2,0clo0ud0?m
(6,550ft)
The average hurricane, with a
radius of about 1,330 kilometres © NASA The eye at the centre of a
(825 miles), can dump as much hurricane tends to be 20-
as 21.3 x 1015 cubic centimetres 50km (12-31mi) in diameter
(1.3 x 1015 cubic inches) of water a
day. That’s enough rain to fill What is a weather front? Thunderstorms Fog
up 22 million Olympic-size
swimming pools! A weather front is the Wet ’n’ wild Unstable masses of Fog often comes
separation between two warm air often contain before the slow-
HOW DO DROUGHTS different masses of air, which If there’s a lot of moving warm front.
AND HEAT WAVES have differing densities, moisture in the cold air stratiform clouds, full
DIFFER? temperature and humidity. of thunderstorms.
On weather maps, they’re mass, the wedge can
Droughts are about an extreme delineated by lines and also cause a line of
lack of water, usually due to lower symbols. The meeting of
than average rainfall, and last for different frontal systems showers and storms.
months or even years. There’s no causes the vast majority of
set definition of a heat wave, but it weather phenomena.
typically means higher than
average temperatures for several Wedge Cold front Warm front
consecutive days. Both can lead to
crop failures and fatalities. As cold air is denser, it Cold fronts lie in deep Warm fronts lie in broad
often ‘wedges’ beneath troughs of low pressure troughs of low pressure and
WHY ARE RAINBOWS the warm air. This lift and occur where the air occur at the leading edge of
ARCH-SHAPED? can cause wind gusts. temperature drops off. a large warm air mass.

Rainbows are arched due to the
way sunlight hits raindrops. It
bends as it passes through
because it slows during this
process. Then, as the light passes
out of the drop, it bends again as it
returns to its normal speed.

WHAT IS THE GREEN
FLASH YOU SEE AS THE
SUN SETS SOMETIMES?

At sunsets (or indeed rises), the
Sun can occasionally change
colour due to refraction. This can
cause a phenomenon called green
flash. It only lasts for a second or
two so can be very tricky to spot.

020

STRANGE DAY AT NIGHT © Martin Koitmäe
BUT TRUE
Noctilucent clouds occur when icy polar mesospheric clouds – the highest
CLOUD LIGHTING clouds in the Earth’s atmosphere at 76-85 kilometres (47-53 miles) – refract
the fading twilight after the Sun has set, temporarily illuminating the sky.

DID YOU KNOW? Fog is made up of millions of droplets of water floating in the air

What is a sea breeze?

Rising heat High pressure Cooler air High pressure

Dry land is heated by the High pressure carries the The cooled air High pressure carries the
Sun, causing warm air to cooled air out over the water. slowly sinks cooled air towards land.
rise, then cool down. down over land.
Cooler air
Rising heat
The cooled air
slowly sinks down In the evening,
over the ocean. the land cools
off faster than
Surface wind Surface wind the ocean.
Warm air rises
Wind over the ocean blows the Wind blows the air back out towards over the water,
cool air back towards land. the ocean. This is a ‘land breeze’. where it cools.

What are red sprites Does lightning ever strike
and blue jets? in the same place twice?

These are both atmospheric and electrical phenomena that take place in the upper atmosphere, and Yes, lightning often strikes twice in the same
are also known as upper-atmosphere discharge. They take place above normal lightning; blue jets location. If there’s a thunderstorm and lightning
occur around 40-50 kilometres (25-30 miles) above the Earth, while red sprites are higher at 50-100 strikes, it’s just as likely to happen again. Many
kilometres (32-64 miles). Blue jets happen in cone shapes above thunderstorm clouds, and are not tall structures get struck repeatedly during
related to lightning. They’re blue due to ionised emissions from nitrogen. Red sprites can appear as thunderstorms, such as New York City’s famed
different shapes and have hanging tendrils. They occur when positive lightning goes from the cloud to Empire State Building or NASA’s shuttle launch
the ground. pad in Cape Canaveral, Florida.

How cold was the
coldest day
in history?

-89˚C (-129˚F)

Recorded on 21 July
1983 at Vostok II
Station, Antarctica

© SPL Why does the
Sun shine?

The Sun is a super-dense
ball of gas, where hydrogen
is continually burned into
helium (nuclear fusion). This
generates a huge deal of
energy, and the core
reaches 15 million degrees
Celsius (27 million degrees
Fahrenheit). This extreme
heat produces lots of light.

021

50 STRANGE WEATHER FACTS

Meteorological marvels

WHAT IS Where are you most likely
CLOUD to get hit by lightning?
IRIDESCENCE?
Generally lightning strikes occur most often during the summer. So
This happens when the place where lightning strikes occur the most is a place where
small droplets of summer-like weather prevails year-round: Africa. Specifically, it’s the
water or ice crystals in village of Kifuka in the Democratic Republic of Congo. Each year, it gets
clouds scatter light, more than 150 lightning strikes within one square kilometre. Roy
appearing as a rainbow of Sullivan didn’t live in Kifuka but he still managed to get struck by
colours. It’s not common because lightning seven separate times while working as a park ranger in the
the cloud has to be very thin, and Shenandoah National Park in the USA. The state in which he lived
the colours are often – Virginia – does have a high incidence of lightning strikes per year,
overshadowed by the Sun. but since Sullivan spent his job outdoors in the mountains, his risk
was greater due to his exposure.
WHAT DO WEATHER
SATELLITES DO? How many Lightning occurs most often
thunderstorms in hot, summer-like climates
The GOES (Geostationary
Operational Environmental break out
Satellite) system is run by the US worldwide at any
National Environmental Satellite, given moment?
Data, and Information Service
(NESDIS). The major element of 2,000
GOES comprises four different
geosynchronous satellites How do tornadoes work? How hot is the Sun?
(although there are other
geo-satellites either with other Polar air Tropical air 15,T0he0co0re ,is0ar0oun0d˚C
uses now or decommissioned). (27,000,000˚F)
A cold front full of very dry The cold front
The whole system is used by air and at high altitude is meets a warm front Why is it so quiet
NOAA’s National Weather Service necessary for a tornado. full of very moist air after it snows?
for forecasting, meteorological and at low altitude.
research and storm tracking. The It’s peaceful after snowfall as
satellites provide continuous Funnel the snow has a dampening
views of Earth, giving data on air effect; pockets of air between
moisture, temperature and cloud The wind begins the flakes absorb noise.
cover. They also monitor solar rotating and forms a However, if it’s compacted
and space activities like solar snow and windy, the snow
flares and geomagnetic storms. low-pressure area might actually reflect sound.
called a funnel.
WHY ARE CLOUDS How many lightning
FLUFFY? Tornadoes start out with severe thunderstorms called strikes are there each
supercells. They form when polar air comes in contact with
Fluffy-looking clouds are a type tropical air in a very unstable atmosphere. Supercells contain a 100second globally?
called cumulus. They form when rotating updraft of air that is known as a mesocyclone, which
warm air rises from the ground, keeps them going for a long time. High winds add to the
meets a layer of cool air and rotation, which keeps getting faster and faster until eventually
moisture condenses. If the cloud it forms a funnel. The funnel cloud creates a sucking area of
grows enough to meet an upper low pressure at the bottom. As soon as this funnel comes in to
layer of freezing air, rain or snow contact with the Earth, you have a tornado.
may fall from the cloud.

WHAT’S IN ACID RAIN?

Acid rain is full of chemicals like
nitrogen oxide, carbon dioxide
and sulphur dioxide, which react
with water in the rain. Much of it
comes from coal powerplants,
cars and factories. It can harm
wildlife and damage buildings.

WHY CAN I SEE MY
BREATH IF IT’S COLD?

Your breath is full of warm water
vapour because your lungs are
moist. When it’s cold outside and
you breathe out, that vapour cools
rapidly as it hits the cold air. The
water molecules slow down,
begin to change form, and bunch
up together, becoming visible.

022

How hot was the Why do clouds look different
hottest day in depending on their height?
history?
Altocumulus Cirrus
58˚C (136˚F)
Patchy clumps and These thin, hair-like
Recorded on 13 layers make up this clouds form at, or above,
September 1922 in mid-level cloud. It often
Al Aziziyah, Libya precludes storms. 5,000m (16,500ft) and
may arrive in advance
What is ball
lightning? of thunderstorms.

This mysterious Stratocumulus Altostratus
phenomenon looks
like a glowing ball of These are low, These very thin, grey
lightning, and floats lumpy clouds clouds can produce a
near the ground usually bringing
before disappearing, a drizzling rain. little rain, but they
often leaving a They may hang may grow eventually
sulphur smell. as low as 300m
Despite many (1,000ft). into stratus clouds.
sightings, we’re still
not sure what Cumulus
causes it.
These vertically
building clouds are

puffy, with a base
sub-2,000m (6,550ft).

Cumulonimbus Stratus

This vertical, dense cloud These low-lying,
heaps upon itself and often horizontal, greyish
brings heavy thunderstorms. clouds often form when
fog lifts from the land.

© SPL What are the
odds of getting
hit by lightning

in a lifetime?

1 in 10,000

What are gravity
wave clouds?

Gravity waves are waves of air moving through a stable
area of the atmosphere. The air might be displaced by an
updraft or something like mountains as the air passes
over. The upward thrust of air creates bands of clouds with
empty space between them. Cool air wants to sink, but if it
is buoyed again by the updraft, it will create additional
gravity wave clouds.

023

DEADLY
WEATHERExplore the Earth’s killer weather

26

26 Surviving 48 Heatwaves
extreme Earth Find out the Met Office’s best
advice for what to do when a
Find out how to survive some heatwave hits
of Earth’s toughest weather

36 Cyclone vs anticyclone 50 Rise of the superstorm
What causes these spinning Discover the science behind
systems of air? Earth’s most dangerous and
deadly tornadoes

38 Megafloods 54 Firestorms
Discover the epic floods that Explore nature’s most violent
shaped our world infernos from tornado-force
winds to the super-hot flames
42 Drought 60
Learn the science behind what
can be a devastating event 58 Monsoons
around the world
The wind systems behind
43 Hurricanes and the weather of Earth’s sub-
typhoons tropical regions

Understand what’s so different 59 Avalanche!
about hurricanes and What causes the deadly
typhoons landslides made of snow?

44 Lightning 60 Killer storms
Find out what’s behind the Marvel the raw power of
phenomena that lights up the nature when it hits you with its
skies in a storm absolute worst

024

DEADLY WEATHER

59

44 58
50
025
54

Surviving extreme Earth

026

Aug 1910 Jan 1911 Sept 1911 Dec 1911 Dec 1911

ROALD AMUNDSEN’S Amundsen and his team The boat reaches the Ross In their first bid to get By reaching 88°23’S, the Amundsen reaches the
EXPEDITION set off from Christiania, Ice Shelf, sailing closer to closer to the Pole, bad team is further south South Pole where he and
Denmark with nearly 100 the Pole than Scott’s team, weather forces them to than anyone has ever
giving them an advantage. race back to their base. travelled before. his team place a
Greenland dogs. Norwegian flag at the site.

Roald Amundsen beat Robert Scott to the South Pole by 34 days, despite Scott beginning eight weeks earlier

Surviving

extreme
Earth

The skills you need to journey into the
wilderness and get out again alive

For many of us, the toughest
conditions we’d ever have to face
would probably be walking the dog in
the bucketing rain. However, outside of the
urban sprawl there are some places on Earth
that aren’t so hospitable to humans. While
mankind has successfully populated large
areas of the planet’s land surface, there are still
many places you wouldn’t dare to venture
unless you really enjoy a challenge or have just
got horribly, horribly lost.
History is littered with people who have
faced the biggest tests this planet has to offer,
whether deliberately or accidentally, and lived
to tell the tale, but many have fallen victim to
frozen wastes or scorching plains. Even the
best-prepared adventurers can come unstuck
in the face of the amazing force of nature.
Over the next few pages we trek across
deserts in search of water, dredge through
jungles and scale icy mountains to uncover the
dangers you’re likely to come up against. Find
out the equipment and skills needed to survive
some of the most mind-boggling and hostile
environments, where temperatures can
plummet in hours and winds can reach
breath-taking speeds.
We’re not saying we will instantly turn you
into the next Ranulph Fiennes, but it will
hopefully give you a fighting chance should you
find yourself in the depths of the Arctic Circle or
in the middle of the Sahara. We still wouldn’t
recommend it though.

027

DEADLY WEATHER

Surviving extreme Earth

Beat the freeze The snowy wastes of
the polar regions are
How to stay alive when you’re freezing to death difficult to navigate

Earth’s north and south extremities are Polar bears are the Little grows in this
among the most inhospitable on the Arctic’s deadliest hunters area so finding food
planet. Even in the summer months is tough
temperatures are near freezing and winds can There is peril at every
reach up to 327 kilometres (200 miles) an hour, so step as one wrong Goggles
it’s no wonder the cold is the biggest killer here. If move can plunge you
you’re trekking across snowy wastes, you better into icy waters The best goggles have a
have packed your thermals. Shrug on multiple photochromic lens to help
layers of breathable fleeces and keep them dry. Life-saving kit ward off glare from the ice
Any water will instantly freeze, as will any and make sure you see
exposed flesh. Even nose hairs and eyelashes A rundown of what to wear to stay warm cracks and holes.
start icing over in minutes, so covering up is key. Hat
Your body will respond quickly to the heat loss Balaclava
by tightening blood vessels near your skin. This A hat with ear flaps that
is the reason we look paler when we’re cold and covers the head and neck You’ll need to cover up as
why our fingers and toes become numb. is vital. A strap to secure it much as possible, so a
Meanwhile, your muscles will start moving on the head will be useful woollen balaclava will keep
involuntarily, causing you to shiver. It can boost in high winds. the most heat in.
heat production up to five times, but that uses up
a lot of energy so you’ll need to keep eating and Thermal shirt Mittens
drinking. Consume six to eight litres (10.6 to 14
pints) of water every day and around 6,000 Your base layer should be a Although gloves offer more
calories, three times the typical recommended thin, thermal insulating top dexterity with actions,
daily allowance. You can get this by melting that wicks any sweat away mittens are better as they
butter into your food or munching on chocolate from your body. keep your fingers together
and bacon, so it’s not all bad! and much warmer.
A word of warning, though: keep your eyes
peeled. Hungry polar bears, particularly those
with cubs to feed, can be aggressive and are
masters of disguise. Flares and loud noises will
often be enough to scare them away. You’ll also
need to watch your step, as slipping through a
crack in the ice can send you plummeting into
the freezing cold ocean. It’s generally safe to
walk on white ice, but grey ice is only ten to 15
centimetres (four to six inches) thick and prone
to cracking, while black ice is to be avoided at all
costs since it will have only just formed. Tread
carefully, stay wrapped up and keep on the
move if you want to have any hope of survival.

Amazing animal Jacket Trousers

The arctic fox is an incredible little animal, well Your jacket will need to be Waterproof and windproof
adapted to living in one of the harshest both wind and waterproof trousers are a must. Make
environments on Earth. Its furry feet and short ears to keep you dry and warm. sure they are also
are ideally suited to conserving heat in the Wrist holes in the cuffs breathable, however, as
unforgiving, freezing environment. Its coat is also keep it secured. you don’t want your legs to
adaptable; while its habitat is snowy its fur is become sweaty and lose
brilliant white, hiding it from both prey and Boots valuable fluid.
predators. However, as the ice melts, its coat turns
brown or grey to hide among the rocks of the region. Warmth is vital – literally
The arctic fox is an omnivore, feasting on rodents, – so fleece-packed boots
fish and birds, but it will also eat vegetation when are good. Straps are better
meat is difficult to find. than laces but don’t fasten
them so tight it cuts off
the blood supply.

028

RECORD -93.2˚c COLDEST PLACE ON EARTH
BREAKERS
A bone-chilling temperature of -93.2°C (-135.8°F) was
DEEP FREEZE recorded in Antarctica in 2010 by satellite, making it
the lowest temperature ever recorded on Earth.

DID YOU KNOW? USA, Russia, Norway, Canada and Denmark all lay claim to territory in the Arctic, but none are allowed to own it

Survive the night

Build an igloo for protection

Find your spot

The first trick to making your igloo is to build it on the
side of a slope. This will mean less building for you to do.
Dig a trench in the snow around 0.6m (2ft) deep. Get in
and slice out blocks of packed ice from either side of the
trench to ensure they are nice and uniform.

Ice fishing AVERAGE DEPTH OF ICE

Make a hole in the ice with an auger – a kind of IN ANTARCTICA – 2,126
drill that bores large holes. The ice you bore on
should be light grey and about 15 centimetres (six METRES (6,975 FEET) Dig yourself in
inches) deep. Produce a hole approximately 0.5 EQUIVALENT TO 6.5
metres (1.5 feet) in diameter. Set up your chair Dig another trench into the side of the hill. It should be
one metre (three feet) away from the hole and
hold your rod over the top of it, with the line 7EIFFE0L TOW%ERS about 0.5 metres (1.6 feet) wide. This is the entrance
dangling in the water. The rod should only be trench. Leave a gap and dig another hole, but don’t make
about a metre (three feet) long and made of a it as deep as the entrance trench. This is your sleeping
sturdy material. Drop the baited line down around chamber, so make sure you fit in it!
two metres (seven feet) and wait for a bite. Reel it ANTARCTICA’S ICE ACCOUNTS
in and keep it chilled before cooking! FOR 70 PER CENT OF THE WORLD’S

This simple tool can FRESH WATER
find you a life-saving
source of food 4 MILLION
PERMANENT
INHABITANTS IN
THE ARCTIC, NONE
IN ANTARCTICA

IF ALL THE ICE IN Construct the walls
ANTARCTICA MELTED,
THE SEA WOULD RISE Stack the ice blocks in a circle around the sleeping trench,
leaving a gap around the entrance trench. Over the
58M (190FT). THE entrance trench, stack the blocks in a semicircle. Make
STATUE OF LIBERTY the entrance tunnel as small as possible to minimise heat
IS 93M (305FT) TALL loss. Rub water over the blocks to fuse them together.

029

DEADLY WEATHER

Surviving extreme Earth

Escape scorching heat Amazing
animal
How to survive the extreme temperatures of the desert
The camel is known as
While the polar regions are always deliver a sting with their tail that can paralyse the ship of the desert, as
bitterly cold no matter what time of and eventually kill. Sturdy boots will protect this remarkable creature
day it is, one of the major challenges in you from these creepy crawlies, as well as can travel without food or
surviving the desert is dealing with the making your travelling over sand much easier. water for a long time.
ridiculous changes in temperature. In the While they don’t make great pets, scorpions do
midday Sun, the mercury can reach as high as provide a crucial source of nutrition. Picking Domesticated 3,000
50 degrees Celsius (122 degrees Fahrenheit) in them up by the tail just behind the stinger is the years ago, camels have been an
the Sahara, but drop to below freezing by night. safest method and it will give you vital protein invaluable help to those who make
Your best bet is to wear a loose-fitting robe. This for your journey. Just don’t eat the tail. their livelihood travelling the desert. They can
will let air circulate around the body and you carry 90kg (200lb) on their backs effortlessly
won’t get nearly as hot and sticky. At night, In the desert, you’ll need to adjust your body and can travel up to 32km (20 mi) a day, with
when the temperature plummets, you can wrap clock. Aim to shelter during the day and travel the added bonus of being able to last for at least
it around you for warmth. at night. This has the dual benefit of avoiding a week without water and months without food.
It is vital that you protect your head. If you the scorching sun and keeping you active
think a touch of sunburn from staying by the during the freezing night. It also means you can Camels store fat in their hump to use as a
pool on holiday is bad, that’s nothing compared keep on the right track easily by following the food source and consume 145l (32gl) of water in
to the effects of walking all day in the parched stars, hopefully leading to civilisation. one go, which they also store for later use. They
desert. Even if it means burning another part of have adapted wonderfully to the desert,
your body, wrap something around your head Shelter can come in the form of large rocks or developing a membrane across the eye and
and neck so you don’t succumb to sunstroke, cliffs. Alternatively, you can dig a trench down extra-long eyelashes to counteract sand storms.
which can lead to hallucinations and fainting. into the cooler sand and use clothing or some Their feet also are incredibly well protected with
Other dangers in the desert will mostly come other material you have available to form a calluses and spread out for walking on sand.
from scorpions. They hide in the sand and canopy over the top, secured by rocks or sand.
As long as it is at an angle and not touching you,
you’ll be protected from the Sun’s glare.

Desert dress

The essentials to surviving in the hottest places on Earth

Headwear Sunglasses

If you don’t have any The desert throws up an
headwear, you could suffer awful lot of sand and glare,
with heatstroke, so protect so sunglasses will be
your face and neck. absolutely vital.

Sleeping bag Water bottle Miles and miles of
sand can leave you
A brightly coloured blanket This will be your greatest hopelessly lost
will be useful as it would friend. Take small, regular
enable any search party to sips and if you ever find a Finding your
find you, will keep you water source, fill it up as way around
protected in the day and much as possible.
warm at night. The desert is not only barren and featureless, but it
Shirt is also a moving entity. Therefore, finding your way
Sun cream around is tough. The easiest way to find your way
Your clothes will need to around is with a compass, but if that isn’t available,
The baking temperatures be as loose fitting as travel at night and use Polaris, the North Star, as
will burn you in no time at possible to minimise your makeshift compass.
all, so a high factor sun sweating and dehydration.
cream will provide at least Even though they are always shifting, sand dunes
some protection. Footwear can also provide useful navigation hints. They
always build up at 90 degrees to the direction of
030 Even though you’ll be the wind, as the wind pushes sand upward to form
desperate for sandals, them, so even when there’s no wind, if you know
trainers or walking boots the wind is northerly, the dunes will go east to west
will give you grip and and you can use that information to navigate.
necessary protection.
If you are lucky enough to have any landmarks,
try and make a straight path between them so you
know you are going in a straight line.

HEAD 1. BIG Gobi Desert 2. BIGGER Arabian 3. BIGGEST Sahara Desert
Desert
2HEAD This 1.3mn km2 The most famous desert
(502,000mi2) rocky At a staggering 2.3mn in the world measures
LARGEST NON- desert covers a large km2 (888,000mi2), the 9.1mn km2 (3.5mn mi2),
POLAR DESERTS portion of China and harsh Arabian Desert making it over three times
Mongolia, experiencing takes up most of the bigger than any other non-
harsh and dry winters. Arabian Peninsula. polar desert.

DID YOU KNOW? Contrary to popular belief, drinking cactus water won’t quench your thirst but make you very ill

Fight extreme thirst

Locate the desert’s most precious resource

70.7°C (159.3°F)

Hottest temperature
ever recorded (Lut
Desert, Iran)

Follow the wildlife 58°C (136.4°F)

There are a number of birds and land animals that live in Hottest Saharan
the desert and they all need water. Try and follow them temperature (Sahara
wherever possible and hopefully they should lead you to a Desert, North Africa)
water source.
56.7°C (134°F)

Hottest directly
recorded temperature
(Death Valley, Arizona)

34.4°C (94°F)

Hottest average yearly
temperature (Afar
Depression, Ethiopia)

THE TEMPERATURE IN CELSIUS Shady cliffs 26°C (78.8°F)
THAT CAUSES HYPERTHERMIA
(OVERHEATING) AND DEATH In your quest for precious shade, you might also be lucky Hottest average
enough to find water. Dips and ridges that face north temperature in Europe
could be housing puddles and pools in their shaded, (Seville, Spain)
cooler spots.
0°C (32°F)

Night temperature in
the Saharan Desert

The plunging temperatures -20°C (-4°F)
can leave you freezing cold
without the right preparation Coldest average
desert temperature
(McMurdo Dry
Valleys, Antarctica)

Grass is always greener -89.2°C (-128.6°F)

Plant life and vegetation means there is water around Coldest directly
somewhere. Head down into valleys where there is plenty recorded desert
of greenery and even if there isn’t a spring or pool around, temperature (Vostok
you should be able to extract water from leaves or roots. Station, Antarctica)

031

DEADLY WEATHER

Surviving extreme Earth

Battle life-threatening altitude

How to cross the world’s most treacherous terrain

Mountains are the ultimate test of hand, try to find a stream or melt some snow or walking in circles. As well as being potentially
survival. They’re prone to rapid ice to drink. confusing, mountains also hide dangerous
changes in weather and it’s near crevices. Keep your eyes peeled for breaks in
impossible to predict. Even if the base is warm The altitude is a real issue for many the snow or ice and if you are ever unsure, try to
and sunny, by the time you reach the summit, mountaineers. As you climb higher, the air find rocks or stones to throw in front of you that
low cloud can blind you, rain can make the pressure reduces, meaning there is less oxygen could give away a hidden abyss.
terrain slippery and the cold can freeze you. for you to breathe. This lack of oxygen will
Good preparation is essential and you’ll need cause your brain to reduce activity in all but the If the visibility does become too poor, the
a lot of kit. Pack a rucksack with a map, most important organs, making your limbs safest thing might be to bed down. Find a spot
compass and a flashlight or headtorch, along heavy and head dizzy. The most important out of the wind and protected from any snow or
with a brightly coloured emergency blanket, thing to do is rest and re-oxygenate your body. rainfall, like a cave or overhanging cliff. Even
and dress in thermals and waterproof and though it might sound strange, pack your
windproof clothing. You’ll also need to keep If you are trying to escape the mountain, the surroundings with snow, because it does have
well hydrated. A lack of fluid at high altitude best way is to head downward, but this isn’t insulating properties. Pile yourself with as
will result in dizziness, intense headaches and always possible. Mountains have complicated many layers as possible and this should provide
even frostbite. If you don’t have any water to structures and often there isn’t an easy path the warmth so you can make it through the
down. If possible, put markers along your route night and try to find your way out in the light.
to show where you have already been, to avoid

Amazing animal GoPros are a Keep a record
great way to
The mountain goat is amazingly adapted to life on record your It’s always handy to have a visual record of your
the mountainside. Their hooves are curved and adventure travel by using a video recorder like the Hero3+
flexible to provide them more grip and traction on from GoPro. This camcorder is incredibly robust,
the treacherous slopes. Despite looking spindly and lightweight and waterproof. It can also be attached
thin, their legs are actually very strong and they onto helmets or bags, leaving your hands free to
can leap surprisingly large distances. scale the treacherous mountainside.

They have two coats, a warm, woolly undercoat Using a GoPro camera will also be useful as, once
and a thinner but longer overcoat, which keeps the you get off the mountain to safety, you and a
insulating undercoat dry. This system is how they professional will be able to look over the footage,
can stand the cold temperatures long after bigger determine what went wrong and see how you could
animals have given up and descended down the avoid getting stuck in the same situation again. The
mountain in cold weather. Hero3+ is available at www.camerajungle.co.uk.

Mountain gear Headlight

What you need to brave the harsh, mountainous environment A powerful headlight will be essential for
finding your way around in darkness
Beanie without wasting a hand on a torch.

A tight-fitting hat will keep lots Coat
of heat in as well as not being
likely to fly away! Lightweight is key here because you don’t
want to be weighed down. Bright colours
Mittens will also make you visible to rescuers.

Although it would be useful to have T-shirt
fingers available for gripping ledges,
it’s more important to have your A tight-fitting T-shirt made of
fingers warming each other. breathable material will keep
body heat in without making
you sweat.

Rope Flare

A strong and sturdy rope will help If you can send up a flare, do so at
you protect yourself while asleep night. Not only will it attract the
and also aid you in climbing or attention of rescuers, it might
negotiating dangerous paths. ward off predators.

Trousers Boots

You need to keep dry and have items A high-legged boot will keep the worst of
accessible, so a pair of waterproof the snow and water out, while the sole will
trousers with zipped pockets will be the need to be rugged and have tons of grip.
most useful.

032

DID YOU KNOW? The tallest volcano is Mauna Kea, as it starts 6,000m (19,685ft) below sea level, making it 10,205m (33,480ft) tall

Keep the fire burning

How to warm up on the mountainside

Find some wood Build your base Light the fire

You’ll want a variety of wood, from small sticks and twigs, Dig a small pit in the ground. Surround it with stones so Place the larger branches and logs at an upwards angle,
all the way up to sizeable branches and logs. The smaller the fire doesn’t get out of control. Place the smallest bits allowing the air to circulate and ensuring all the wood is
bits will light much more quickly while the bigger pieces of wood at the bottom of the pile, but leave some gaps to getting burned evenly. Make sure everything is connected
will burn longer, hotter and form the bulk of the blaze. keep the fire supplied with the oxygen it needs to burn. so fire can transfer from one piece of wood to another.

The weather can turn in an
instant, so make sure you’re
prepared for anything

Crevices and cracks await
the unwary traveller

DEADLY WEATHER

Surviving extreme Earth

Ben Fogle vs Ben struggled through one
Mother Nature of the toughest foot races
in the world

TV’s most charismatic survivalist has taken The Race to the Pole Cracknell. The pair crossed the 4,717 kilometres
on ocean rows, desert marathons and polar required a lot of hard work (2,931 miles) in 49 days, 19 hours and eight
expeditions. We got the chance to ask him and calories minutes, finishing second overall in the pairs
how and, more importantly, why classification. “I was looking for a challenge to
Sahara Desert. Those taking part have to make me stronger”, he says. “I applied for the
Ben Fogle first exploded onto the contend with scorching heat, terrible blisters Atlantic Rowing Race and then set about
survivalist scene as the star of BBC and sand storms. Despite this, Ben managed to finding myself a rowing partner. We spent a
series Castaway 2000. 13 years later, he’s finish the race in less than 60 hours. “Anyone year getting ready for it. It was a gruelling
riding a camel, commando. “The desert is who has raced the MdS will know there are experience, we capsized and nearly drowned
unforgiving; I wish I had worn pants”, he laughs, points when you want to give up, but it’s not so but, as they say, what doesn’t kill you makes
recalling the time he followed in the footsteps of easy in the middle of the Sahara”, he explains. you stronger.”
legendary British adventurer Sir Wilfred “You can’t just jump on a bus.”
Thesiger, crossing a brutal stretch of Middle
Eastern desert. “We did it authentically, wearing Having conquered the Sahara Desert, two
original clothes as worn by Thesiger. He didn’t years later Ben entered the epic Atlantic Rowing
wear undergarments and neither did I. But Race with former Olympic rower James
chafing aside, the trek across the Empty Quarter
of Oman was the most enjoyable thing I’ve ever
done because it was a lifelong ambition.”
The then 40-year-old’s rapid adjustment to the
challenging environment shouldn’t really have
come as a surprise, considering his varied,
outdoorsy early years. “I spent all my summers
in Canada at the cabin my late grandfather
handbuilt on a lake. It was an idyllic Swallows
And Amazons childhood of tree houses, fishing
and raft building. I did a degree in Latin
American studies after spending two years
living in the colourful continent. I loved it and
wanted to learn more. My degree included a
one-year overseas programme so I went to Costa
Rica. I would recommend Central and South
America to anyone.”
A stint on Castaway 2000 followed, in which
Fogle and 35 other men, women and children
tried to build a community on the Scottish Island
of Taransay. It was a hotbed of disagreement,
argument and drama but he managed to rise
above it, becoming one of the stars of the show. “I
applied for Castaway 2000 because I was looking
for an excuse for adventure”, he says. “I liked the
idea of spending a whole year marooned on a
remote island. The experience was life changing
in every sense. It taught me so many life skills
that still serve me today.”
The social experiment ended a year later and
back in London, the TV presenting jobs came
flooding in. But with adventuring clearly in his
blood, Ben sought another challenge and
decided to take part in the Marathon des Sables
(MdS). This epic six-day race, known as the
toughest footrace in the world, takes runners
around 240 kilometres (150 miles) through the

034

5TOP The conservationist The driver Famous mum The boxer Famous dad
FACTS
1 While in South America, Ben 2 Fogle is a man of many 3 His mother is actress Julia 4 He took on and beat 5 Ben’s father, Canadian-born
THE LIFE OF BEN Fogle worked on a turtle talents, certified to skipper a Foster, best known for roles EastEnders’ Sid Owen in a Bruce Fogle, is also
conservation project on the variety of boats, yachts and in Alfie, The Loneliness Of charity boxing match in aid something of a celebrity,
Mosquito Coast of Honduras, dinghies as well as holding The Long Distance Runner of Sport Relief back in hosting many TV and radio
as well as volunteering in an licenses for SCUBA diving and Half A Sixpence, among 2004. He trained for six shows in Britain in his role
Ecuadorian orphanage. and rally driving. many others. weeks for the fight. as a veterinarian.

DID YOU KNOW? The Marathon des Sables was created by Patrick Bauer, who crossed the Sahara in 12 days

Despite going to all corners of the
globe, Ben still has more challenges
to take on

Not content with rowing all the way across the Shrosbree. We had to bulk up before the race and City investigates the effects of our planet’s © Alamy; Ed Crooks; Thinkstock
second biggest ocean on the planet, the harsh take 5,000 calories of food per day for the race extreme weather. “One of the hardest things I
Antarctic was Fogle’s next challenge, once again itself. The kit is essential to survival and we took have to face on my trips is disease and poverty”,
teaming up with James Cracknell to take on the advice from people who had previously trekked he says. “I still hate to see suffering in the world.
Race To The Pole, a team event that transports in Antarctica. The most important thing to It makes me feel guilty for what I have. Having
competitors to the southernmost tip of the remember is never sweat. Sweat and you die. It’s said that, my job allows me to explore the world
planet. “Antarctica is the coldest, driest, difficult to race and not sweat.” and meet incredible people.”
windiest place on Earth,” Fogle recalls. “It’s a
desolate, tough, unforgiving environment. We In recent years there’s been no avoiding a spot As someone who’s visited most of the hostile
trained in Norway with the Marines and on a of perspiration, as his series Extreme Dreams places on Earth, there aren’t many options left
Swiss glacier with personal trainer Bernie took him to the jungles and mountains of South for his next extreme expedition, but he’s got a
America and Africa, and his latest show Storm spot in mind. “The Moon. Watch this space.”

035

DEADLY WEATHER

Cyclone vs anticyclone

Cyclone vs anticyclone

What causes these spinning systems of air and how do they differ?

Cyclones and anticyclones are
generated when areas of high and low
air pressure collide. These are created
by differences in temperature and humidity.
Air temperature affects the molecules’ kinetic
energy. The higher the temperature, the more
the molecules move and collide. Humidity, on
the other hand, affects the air itself. The
atmosphere’s main constituents – diatomic
oxygen and nitrogen – are heavy compared to
water vapour. The water in humid air replaces
some of the heavier molecules, making it lighter
than dry air, and therefore of a lower pressure.
An anticyclone is a region of high
atmospheric pressure. The air descends
through the system, spreading out sideways as
it makes contact with the ground. The
compressed air causes a rise in temperature –
hence why anticyclones are associated with
summer weather and dry winter days.
In contrast, a cyclone is centred around a
region of low pressure. Inward spinning winds
draw air upwards into the system – as it rises,
water vapour cools and condenses, resulting in
cloudy weather and storms.

036

Hurricanes and cyclones form © NASA; Thinkstock
as a result of rapid shifts in air

pressure and temperature

037

DEADLY WEATHER

Megafloods

Megafloods
Epic floods shaped our world but could they happen again today?

North-west America hosts some of the glacial Lake Missoula. During the last ice Water escaping from natural dams or glaciers
the strangest and most spectacular age, this lake formed behind a 610-metre is responsible for many of the biggest floods,
landforms on our planet. Scarred into (2,000-foot)-tall wall of ice. When this dam including Lake Missoula. Gibbard continues:
the black rock are giant channels carved out by failed, around 15,000 years ago, the lake “You get substantial flooding if a major dam
water – the largest is the Grand Coulee in emptied in just 48 hours and the waters carved floods and releases water.”
Washington at 97 kilometres (60 miles) long. the Grand Coulee. They left ripples, like those
In 1922, geologist J Harlen Bretz began on a streambed, but a monstrous nine metres Among them is the megaflood that turned
investigating how these channels formed. He (30 feet) high. The process would repeat itself Britain into an island around 450,000 to 200,000
initially attributed them to the slow action of over the next 2,000 years, carving out more years ago, when sea levels were lower than
rivers, but the more he looked into it, the more colossal landmarks in North America. today. A gigantic lake formed in what is today’s
unusual landforms he discovered. Among them North Sea behind a chalk ridge that once
were piles of gravel some ten storeys high and Lake Missoula might be the biggest known connected Britain to France by land. When the
hills shaped like boat prows. megaflood, but it’s by no means the only one. lake punched through the natural dam,
These gargantuan features were best Indeed, during the last 1.8 million years, at least floodwaters gouged a huge valley into the
explained by water tearing through the 27 gigantic freshwater floods have shaped our English Channel seabed (see the thermal
landscape – an unimaginably massive planet, carrying more than 100,000 cubic imagery on the opposite page).
megaflood. The prow-shaped hills pointed in metres (3.5 million cubic feet) of water every
the direction of flow, while the gravel was second – equivalent to over 30 Niagara Falls! Other massive floods occurred when sea
dropped when the floodwaters receded. levels rose after an arid spell. For instance,
Bretz tracked the source of this colossal We know less about giant floods from further around 5.3 million years ago, Atlantic waters
torrent – possibly the largest flood in history – to back in Earth’s history. “As you go back in time, spilled into the dried-up Mediterranean; the
you don’t have the landforms preserved,” says ocean eroded a channel through the Strait of
ice-age geologist Professor Philip Gibbard. Gibraltar, filling the sea in as little as two years.

038

5TOP Maeslant Barrier Thames Barrier St Petersburg Dam West Closure Complex Delta Works
FACTS
1 Earth’s largest movable storm 2 This movable flood barrier is 3 The gigantic barrier includes 4 The world’s biggest pump 5 Described by some as a
FLOOD DEFENCES surge barrier defends one of Earth’s biggest and 11 dams and is topped by a station – designed to blast ‘wonder of the world’, this
Netherlands’ Rotterdam from protects London against the six-lane motorway. It was floodwaters back out to sea huge series of 300 dams,
floods. It spans a waterway North Sea. When raised, each completed in 2011 after 300 – is among £8.5bn ($14bn) of sluices and storm surge
360m (1,200ft) across – as of its ten steel gates is the years of almost yearly floods works to protect New Orleans barriers protects the low-lying
wide as the Eiffel Tower is tall. height of a five-storey building. in the former Russian capital. from future hurricanes. Netherlands from the sea.

DID YOU KNOW? Nearly half of flash-flood deaths occur in vehicles. Just 0.6m (2ft) of water can set a car afloat

Water world Sea level rise Present day Biggest
floods in
What role have ancient floods played in Rising sea levels Humans build on history
forming the planet we know today? caused saltwater to flood plains, dam
flood into marine rivers and chop 1 Altai Mountains, Asia
Dinosaur graveyard basins, such as the down trees – What may possibly be the
Mediterranean. increasing the biggest flood of all time
Ancient floods drowned risk of floods. occurred around 12,000 years
prehistoric species, creating ago. Ice dams collapsed on
fossil sources, such as two interconnected lakes,
76-million-year-old dinosaur emptying them into the
bones in western Canada. Mediterranean Sea in an
estimated five hours.
Prehistoric floods Ancient sediments Ice ages
2Wasilla, Alaska
Floods occur anywhere Evidence of prehistoric Sea levels fell during ice When the glacial Lake
there is water. When megafloods includes mineral ages. The ice formed Atna in Alaska breached a
floodwaters retreat, deposits – such as natural dams across natural ice dam around 17,000
nutrient-rich sediments microscopic zircon grains – rivers, which collapsed years ago, the megaflood
are often left behind. dropped far downstream to cause megafloods. released as much as 1,400km3
from their source. (336mi3) of water – that’s
enough to cover the area of
This thermal image of Washington DC in water
the English Channel is 8km (5mi) deep!
evidence of an ancient
megaflood that carved 3Bonneville flood,
out the channel and North America
made Britain an island
During a wet period 14,500
years ago, Lake Bonneville
overflowed its basin. The
floodwaters stripped soil,
filled a 100m (330ft)-deep
canyon to the brim and
created immense and
powerful waterfalls.

4Yarlung-Tsangpo
Gorge, Tibet

Gigantic lakes trapped in the
Himalayas by ice dams helped
erode this majestic gorge
– which is possibly Earth’s
deepest. Evidence exists of
several megafloods in the
gorge during the last 2.5
million years.

5Black Sea deluge
The biblical story of Noah
and the great flood might well
be based on a real historical
event. Rising sea levels
around 7,500 years ago may
have flooded the Black Sea,
destroying human
settlements in the process.

039

DEADLY WEATHER

Megafloods

Megafloods can also have a massive impact But that doesn’t count megafloods out volcano erupts and breaches the barrier
on the climate. The Lake Agassiz flood, for altogether. Among the 27 known big freshwater holding the water in the crater. You can get a
example, is blamed for a cold spell 12,900 years floods in the last 1.8 million years, eight deadly mudflow, sweeping away everything in
ago that sent North America’s large mammals, occurred after 1900. According to Gibbard: “We its path.” An example is Lake Taupo, New
like the woolly mammoth, extinct. Floodwaters could experience a megaflood today. Look no Zealand’s largest lake, which flooded during an
poured into the North Atlantic, interfering with further than Iceland where we see jökulhlaup.” eruption some 1,800 years ago.
the ocean circulation that brings warm water to
the poles, known as the Gulf Stream. Jökulhlaup, or glacier bursts, occur when a Debris from volcanoes can also block rivers.
volcano erupts under an ice cap, such as the An eruption in Mount St Helens about 2,500
Fortunately floods as large as Lake Agassiz or 1996 Vatnajökull eruption in south-east Iceland. years ago caused Spirit Lake to empty
Missoula are unlikely to happen today. The A torrent of meltwater flooded from beneath the catastrophically. More than 260,000 cubic
biggest deluges were associated with giant ice ice, wiping out anything that stood in its way, metres (9.2 million cubic feet) of water per
sheets that swathed the northern hemisphere including bridges, roads and power lines. It’s second flooded downstream. This was like a
during the last ice ages. The ice released estimated that peak flows reached 50,000 cubic bathtub overflowing by comparison to Lake
torrents of meltwater and trapped huge lakes metres (1.8 million cubic feet) of water per Missoula, though, which emptied at an
behind ice dams, which gradually succumbed second in this massive jökulhlaup. incomprehensible 17 million cubic metres (600
to global warming. Only the Greenland and million cubic feet) per second. Similar floods
Antarctic ice sheets, and a few ice caps, remain. Another cause of giant floods, says Gibbard, is would have been likely after the 1980 eruption
where “you have a volcanic lake, and the

Focus on flash floods

In August 1997, an Arizona desert canyon 1. Heavy rain
became a death trap for 11 hikers when they
were caught out by a flash flood. A sudden A torrential rainstorm is
thunderstorm quickly filled the narrow walls with triggered by air rising and
tumbling water and they had nowhere to escape. cooling over high ground.

Flash floods occur within a few hours of 2. Waterlogging
violent rainfall. Although hard to believe, they are
common in deserts, which lack the soil to soak Rain falls too fast to soak
up incoming rain. Water hurtles downhill over up because the ground is
bare rock, rapidly turning creeks kilometres from waterlogged, baked hard
the storm into raging rivers. or impermeable rock.

Desert plants like blue palo verde
depend on flash floods for survival; the
fast-moving water disperses seeds
downstream and abrades their
hard coating, helping
them to germinate.

4. River rises 3. Steep valley The walls of Antelope
Canyon, AZ, have been
The waters rise The excess water
dramatically, often races down steep shaped by repeated
within two hours of slopes into the river, flash floods
the start of the storm. driven by gravity.

5. Banks burst

Unable to
accommodate the
deluge, the river
abruptly bursts its
banks and gushes
across the valley floor.

6. Flooded out

The thundering
waters can sweep
away anything in their
path, turning roads
into rivers and turning
buildings into islands.

040

DID YOU KNOW? Floods are the deadliest natural disaster, responsible for an estimated 500,000 deaths between 1980 and 2009

of Mount St Helen’s if mitigation measures Human activity – such as building hard know volcanoes erupt under ice caps in Iceland.
weren’t undertaken and the lake had not been tarmac roads – is making river flooding even People are trying to predict volcanic activity,
drained via a pipeline. worse, warns Gibbard. “The inevitable but we’re not there yet.”
consequence of covering the landscape with
So how do these megafloods compare to more impermeable materials is like wrapping it in a The next ‘megaflood’ might come from a
common flooding events, like we’ve seen in polythene bag. [More and more] water runs man-made dam rupturing during an
recent months? “They’re orders of magnitude straight into our rivers.” earthquake. Gibbard explains, “Anywhere
greater,” explains Gibbard: “We’re talking stuff where water is stored on less-than-firm ground
that’s incredibly dramatic. Much larger scale With sea levels predicted to rise dramatically might go. The sheer height of water behind
than conventional flooding of rivers.” this century – and climate change likely to those barrages must be enormous.”
boost storm power and frequency – the risk of
Rivers bursting their banks are the most coastal flooding is also on the rise. It’s a real risk. Out of 85,000 American dams,
common cause of flooding today. Excessive rain over 4,400 are considered liable to failure.
or rapid snowmelt can overfill a river channel, Coastal flooding occurs when a storm blows Among them is the Lake Isabella Dam in
causing water to spill out over low-lying land. seawater inland or when a tsunami – a giant California. A strong earthquake could send
Waterlogged or parched soil can also cause wave usually generated by an oceanic around 700 million cubic metres (2.5 billion
water levels to rise rapidly. Even a little rainfall earthquake – hits the shore. cubic feet) of water tumbling downriver. For
cannot be soaked up by the ground so rush now though the best we can do is never to
straight into the river, causing a flood. The big question is, can we predict future underestimate the mighty power of water.
megafloods? “Not easily,” says Gibbard. “We

A giant ice dam rupturing under the weight of The Thames Barrier is an
Lake Missoula is responsible for the megaflood engineering marvel, protecting
that carved out the Grand Coulee (inset) London from high tides

5 How we defend © Professor Sanjeev Gupta and Dr Jenny Collier, Department of Earth Science and
against floods Engineering, Imperial College London; SPL; Thinkstock; Corbis
ON THE 4 3
6 An estimated 37 per cent of the world’s population
MAP live within 100 kilometres (62 miles) of the coast
12 – many in major cities like London, New York and
Flood-prone places Tokyo. They are at risk of flooding from unusually
around the globe high tides and storm surges.

1 India Many cities protect themselves from this threat
2 Bangladesh with hi-tech barriers, dams or sluice gates. For
3 Guangzhou, China example, the Thames Barrier downstream of
4 New Orleans, USA London is a set of gates that lie flat on the riverbed
5 The Netherlands when open. The gates rotate upright when a storm
6 Ho Chi Minh City, Vietnam surge heads inland from the North Sea, or heavy
rainfall raises the river level of the Thames enough
that normal tides will cause flooding. Each gate can
hold back 90,000 tons of water.

Other flood defence systems have permanent
dams with sliding sluice gates to control water flow.
The Oosterscheldedam in the Netherlands – the
largest tidal barrier on Earth – is nine kilometres (5.6
miles) long and has 62 colossal gates; these raise to
make the structure watertight.

New Orleans was flooded in Hurricane Katrina in
2005 – one of the deadliest storms in US history.
Much of the city lies below sea level and depends
on man-made embankments to keep out water.
During the hurricane, these levees broke. The US
Army is renovating the levees and building new
defences, including a pumping station able to pump
540 cubic metres (19,000 cubic feet) of rainwater
every second – enough to empty an Olympic-sized
swimming pool in five seconds.

041

DEADLY WEATHER Drought occurs when an
extended period of high
Drought pressure brings very little rain

What causes
drought?

How a slight shift in wind patterns
can have terrible consequences

For areas that rely on regular rainfall to thunderstorms across the region. Above these example, if the air that normally descends over the
nourish vegetation, animals and a large storms, the jet stream – a current that flows tropics in the Northern Hemisphere is carried
human population, drought can be through Earth’s upper atmosphere – carries the air further north by the jet stream, it can bring
devastating, but in other parts of the world, hot, towards higher latitudes until it eventually extended periods of high pressure to Europe. This
dry weather is a normal everyday occurrence. descends over the tropics to the north and south of can cause precipitation levels to fall below the
These arid climate conditions are caused by the equator. As it falls, it creates a high-pressure expected average for the region, resulting in a
circulatory patterns of air in the Earth’s system that is responsible for the arid conditions period of non-seasonal drought.
atmosphere, known as Hadley cells. of the Sahara and other deserts that populate this
In this weather system, intense exposure to particular region. Despite using advanced weather prediction
sunlight at the equator causes warm, moist air to models, experts are still only able to forecast
rise. As the air rises, it cools again, forming a Slight changes in this movement of air can drought when it is less than a month away, making
low-pressure system that results in regular result in unusual – and sometimes catastrophic – it hard for countries to be prepared. If not, the
weather activity, such as flooding and drought. For impact can be extremely severe.

Convergence and divergence Ascending air Low pressure

How the movement of wind creates wet and dry weather As the converging The rising air creates a
air has nowhere else low-pressure system
Descending air and condenses to form
to go, it rises, clouds that create rain.
The void left by the causing it to cool.
diverging air at the
surface is filled by warm
air sinking from above.

Diverging winds Converging
winds
When the wind blows
two masses of air When the wind
blows two masses
away from each other
they rotate outwards, of air towards
each other they
or diverge. rotate inwards,

or converge.

High pressure © Getty

The descending air
creates a high-pressure
system, bringing with it
clear, dry weather.

042

DID YOU KNOW? Typhoon Haiyan was one of the strongest cyclones ever recorded, killing at least 6,300 in Southeast Asia

Where: Tropical Pacific
Ocean: Pacific Ocean

Hurricanes A storm name is retired
and typhoons if, like Katrina, it has had

catastrophic effects

Is there such a thing as the ‘perfect storm’?

Fishermen who make their living out on air, these weather systems usually form between Northwest Pacific they’re known as typhoons; and
the waves, battling everything the Pacific June and November, and need to reach 120 in the South Pacific and Indian Ocean the weather
Ocean has to throw at them, will tell you kilometres per hour or more to be classified as a system is termed a cyclone.
that this is one of the cruellest oceans to be found hurricane, typhoon or cyclone.
on Earth. Hurricanes can travel huge distances across
It’s the tropical region that whips up this These three terms describe the same event, and oceans, spinning anti-clockwise when in the
meteorological frenzy and creates the mother of the distinction just depends on where the origin Northern Hemisphere and clockwise in the
all storms: hurricanes. Fed by very warm, moist of the storm is located. In the Atlantic and Southern Hemisphere, fed by the warm
Northeast Pacific the storms are hurricanes; in the conditions of the tropics.

Cloud formation Warm air continues to rise and cool Eye of the storm Cool, dry air sinks Outflow of
cold air

Air sucked inwards to updraft Clouds begin to spin

Hurricane formation How the vast, swirling storms begin life at sea Warm, moist air rises in bands

© Corbis; Getty; NASA; SPL 1Cloud formation 2Rotation begins 3Mature storm
Over warm, tropical waters, seawater begins to The warm air continues to rise, cool and suck Warm, moist air continues to rise from the ocean
evaporate. As it rises, it cools to rapidly form clouds. in more air from the surroundings below, gaining and forms clouds in bands around the eye of the
Cooler air from the surrounding area rushes in to energy. As the Earth rotates, the clouds start to storm. Cool, dry air sinks through the eye and also
replace the warm air, which then warms up and rises spin too. A hurricane is formed once wind speeds flows out between the cloud bands at the edges of
again, causing updrafts. reach 120km/h. the storm.

043

DEADLY WEATHER

Understanding lightning

Lightning
Capable of breaking down the
resistance of air, lightning is
a highly visible discharge of
electricity capable of great
levels of destruction. But
how is it formed?

Intense upthrust of volcanic particles
can help generate lightning.

Lightning occurs when a region of cloud and a negative one to the larger ice-water mixture, meets it and completes the connection, generating a
attains an excess electrical charge, either with the former rising to the top on updrafts and the return stroke that due to the channel now being the
positive or negative, that is powerful latter falling to the bottom under the effect of gravity. path of least resistance, returns up through it to the
enough to break down the resistance of the The consequence of this is gradual charge cloud at one-third the speed of light and creating a
surrounding air. This process is typically initiated by separation between the upper and lower parts of large flash.
a preliminary breakdown within the cloud between the cloud.
its high top region of positive charge, large central This leader-return stroke sequence down and up
region of negative charge and its smaller lower This polarisation of charges forms a channel of the ionised channel through the air commonly
region of positive charge. partially ionised air – ionised air is that in which occurs three or four times per strike, faster than the
The different charges in the cloud are caused neutral atoms and molecules are converted to human eye is capable of perceiving. Further, due to
when water droplets are supercooled within it to electrically charged ones – through which an initial the massive potential difference between charge
freezing temperatures and then collide with ice lightning stoke (referred to as a ‘stepped leader’) areas – often extending from ten to 100 million volts
crystals. This process causes a slight positive charge propagates down through towards the ground. As – the return stroke can hold currents up to 30,000
to be transferred to the smaller ice crystal particles the stepped leader reaches the Earth, an upwards amperes and reach 30,000°C. Typically the leader
connecting discharge of the opposing polarity stroke reaches the ground in ten milliseconds and

044

5 TOP Technicolour Zeus Harvest Fawksio Flashmaster
FACTS
1 The super-rare ball lightning 2 The ancient Greeks believed 3 Since 1980 lightning has been 4 In 1769 in Brescia, Italy, 5 From satellite data, scientists
LIGHTNING can materialise in different that lightning was the product looked at by energy companies lightning struck the Church of postulate that there are
colours, ranging from blue of the all-powerful deity, as a possible source of energy, St Nazaire, igniting 100 tons of roughly 1.4 billion lightning
through yellow and on to red. It weather controller and sky with numerous research gunpowder in its vaults. The flashes a year. 75 per cent of
is also typically accompanied god Zeus. His weapon for projects launched to explosion killed 3,000 and these flashes are either cloud-
by a loud hissing sound. smiting was the lightning bolt. investigate its potential. destroyed a sixth of the city. to-cloud or intra-cloud.

DID YOU KNOW? The peak temperature of a lightning bolt’s return-stroke channel is 30,000°C

Explaining the Cloud-to-cloud Cloud-to-air
formation of lightning
Cloud-to-cloud lightning discharges occur Similar to cloud-to-cloud, cloud-to-air strikes
between polarised areas of differing charge, tend to emanate from the top-most area of a
however here the ionised channel runs between cloud that is positively charged, discharging
clouds instead of a cloud to the ground. through an ionised channel directly into the air.

-40 oC Centre of -40 oC
positive charge

-15 oC Centre of -15 oC
-5 oC negative charge -5 oC
Small centre of
positive charge

Cloud-to-ground Intra-cloud Charge differential

Cloud-to-ground lightning occurs when a channel of Intra-cloud lightning is the most frequent type Clouds with lightning-generating potential tend to consist of
partially ionised air is created between areas of
positive and negative charges, causing a lightning worldwide and occurs between areas of differing three layers of charge, with the top-most part a centre of
stroke to propagate downward to the ground.
electrical potential within a single cloud. It is responsible positive charge, the middle a centre of negative charge, and
the return stroke reaches the instigating cloud in
100 microseconds. for most aeroplane-related lightning disasters. the bottom a secondary small centre of positive charge.

Lightning, however, does not just occur between “Due to the massive potential difference
clouds (typically cumulonimbus or stratiform) and between charge areas the return stroke
the ground, but also between separate clouds and can hold currents up to 30,000 amperes
even intra-cloud. In fact, 75 per cent of all lightning and reach 30,000°C”
strikes worldwide are cloud-to-cloud or intra-cloud,
with discharge channels forming between areas of© Science Photo Library Atmospheric lightning
positive and negative charges between and within Altitude (km)
them. In addition, much lightning occurs many Unseen apart from by satellites, a major part of the world’s annual
miles above the Earth in its upper atmosphere (see lightning is generated in Earth’s upper atmosphere
‘Atmospheric lightning’ boxout), ranging from types
that emanate from the top of clouds, to those that 100 Thermosphere Elves
span hundreds of miles in width. Mesosphere
Vast 250-mile wide flattened discs of light, elves
Interestingly, despite the high frequency of occur above low-lying thunderstorms. They are
lightning strikes and their large amount of caused by the excitation of nitrogen molecules
contained energy, current efforts by the scientific due to electron collisions in the atmosphere.
community to harvest its power have been fruitless.
This is mainly caused by the inability of modern 50 Sprites
technology to receive and store such a large Stratosphere
quantity of energy in such a short period of time, as Sprites are caused by the discharges of positive
each strike discharges in mere milliseconds. Other 10 Troposphere lightning from thunderclouds to the ground.
issues preventing lightning’s use as an energy They vary in colour from red to blue and appear
source include its sporadic nature – which while akin to large jellyfish.
perfectly capable of striking the same place twice,
rarely does – and the difficulties involved in Blue jets
converting high-voltage electrical power delivered
by a strike into low-voltage power that can be stored Emanating from the top of cumulonimbus
and used commercially. clouds and stretching in a cone shape up into
the stratosphere and mesosphere, blue jets are
caused by intense hail activity within a storm.

045

DEADLY WEATHER

Understanding lightning

Lightning types Lightning Multiple strikes
hotspots
Far from uniform, lightning is an The Empire State Building is
unpredictable phenomenon A look at some of the most dangerous struck 24 times per year on
places to be when lightning strikes average. It was once struck
Bead lightning eight times in 24 minutes.
Danger zone
A type of cloud-to-ground lightning where the strike
seems to break up into smaller, super-bright sections (the Ten per cent of all people
beads), lasting longer than a standard discharge channel. struck by lightning were
in Florida at the time.
Frequency: Rare
© Scotto Bear 70% OF GLOBAL
Ribbon lightning LIGHTNING OCCURS
IN THE TROPICS
Only occurring in storms with high cross winds and
multiple return strokes, ribbon lightning occurs when © Christian Artntzen
each subsequent stroke is blown to the side of the last,
causing a visual ribbon effect. © Cgoodwin Flashes Global
hotspot
Frequency: Quite rare ‘Damn! And to think that tree was Above the Catatumbo River in
just two months from retirement’ Venezuela lightning flashes The small village of
Staccato several times per minute 160 Kifuka is the most
lightning nights of the year. struck place on
Earth, with 158
A heavily branched strikes per square
cloud-to-ground kilometre per year.
lightning strike with
short duration stroke and What are the chances?
incredibly bright flash.
The odds of being hit by lightning aren’t as slim as you think…
Frequency: Common
1 in
Sheet lightning 3,000,000

A generic term used to describe The chance of you getting struck
types of cloud-to-cloud by lightning is one in 3 million.
lightning where the discharge Which, while seeming quite
path of the strike is hidden from unlikely, did not stop US park
view, causing a diffuse ranger Roy Sullivan from being
brightening of the surrounding struck a world record seven times
clouds in a sheet of light. during his lifetime.

Frequency: Common

Megalightning

A term commonly used when referring to upper-
atmospheric types of lightning. These include sprites, blue
jets and elves (see ‘Atmospheric lightning’ boxout) and
occur in the stratosphere, mesosphere and thermosphere.

Frequency: Frequent

Ball lightning

Considered as purely hypothetical by meteorologists, ball
lightning is a highly luminous, spherical discharge that
according to few eyewitnesses last multiple seconds and
can move on the wind.

Frequency: Very rare

046

HEAD MOST CLASSICAL MOST FUTURISTIC MOST IMMORTAL

2HEAD 1. Percy Jackson & 2. Back To The Future 3. Highlander
The Lightning Thief
LIGHTNING Protagonist Marty McFly travels back in An immortal Scottish swordsman must
IN FILMS A film in which Percy ‘Perseus’ Jackson, son time in Doc Brown’s time travelling, confront his last two rivals in order to win
of Poseidon, must fight mythological beasts lightning-inducing DeLorean, in order to the fabled ‘Prize’. Of course, each time a
and travel to Hades to retrieve Zeus’ stolen ensure his parents hook-up and foe is vanquished his power is absorbed
lightning bolt in order to prevent a war. guarantee his own existence. in a lightning strike.

DID YOU KNOW? The irrational fear of lightning is referred to as astraphobia

Cloud-to-cloud lightning streaks What happens when you
across the Masai Mara Game get struck by lightning?
Reserve in Kenya, Africa

The parts of the body that feel the effect if struck by lightning

© Science Photo Library When a human is hit by lightning, part of Audio visual Organs
the strike’s charge flows over the skin –
Deadly referred to as external flashover – and part Eyes and ears are Organ failure is
of it goes through them internally. The commonly affected also statistically
In July 2007, 30 people more of the strike that flows through, the by a strike, with probable. Death by
were killed by lightning more internal damage it causes. The most hearing loss, tinnitus
in the remote village of common organ affected is the heart, with and blindness cardiac or
Ushari Dara in the majority of people who die from a common. Many of cardiopulmonary
northwestern Pakistan. strike doing so from cardiac arrest. Deep these
tissue destruction along the current path neuropsychiatric arrest is the
Singapore strikes! can also occur, most notably at the problems develop main source of
entrance and exit points of the strike on over time. death for lightning
Singapore has one of the world’s highest the body. Lightning also causes its victims strike victims.
rates of lightning activity. to physically jump, which is caused by the Muscles
charge contracting the muscles in the Skin
body instantaneously. Muscles
contract When struck
Burns are the most visible effect of instantly on a portion of
being struck by lightning, with the strike, causing the strike’s
electrical charge heating up any objects in the victim to
contact with the skin to incredible levels, jump and suffer charge flows
causing them to melt and bond with the muscular over the skin,
human’s skin. Interestingly, however, seizures. while the rest
unlike industrial electrical shocks – which flows through
can last hundreds of milliseconds and
tend to cause widespread burns over the the body
body – lightning-induced burns tend to be internally.
centred more around the point of contact, Skin burns
with a victim’s head, neck and shoulders and hair loss
most affected. are common
side effects
Post-strike side-effects of being as well as the
struck by lightning range from bonding of
amnesia, seizures, motor control worn fabrics.
damage, hearing loss and tinnitus,
through blindness, sleep disorders,
headaches, confusion, tingling and
numbness. Further, these symptoms do
not always develop instantaneously, with
many – notably neuropsychiatric
problems (vision and hearing) –
developing over time.

in comparison…

1 in 14,000,000 1 in 11,000,000 Body tissue Nervous
system
The chance of winning Flying on a single-trip Deep tissue
the lottery in the UK is one commercial air flight destruction is Motor control
in 14 million. That is over inflicts you to a one in 11 common along damage is common,
four and a half times as million chance of being the current path,
unlikely as being struck. killed in an accident. which courses often permanently
through the affecting muscle
1 in 12,000,000 1 in 8,000 © Science Photo Library body from
cranium to feet. and limb movement,
The odds of getting hit by In order to get better neural circuitry and
motor planning and
lightning likelier when in odds, go out in your car. execution decisions.

the UK the chance of dying Over 3,000 people are

from Mad Cow Disease is killed every day on

one in 12 million. roads worldwide.

047

DEADLY WEATHER

Heatwaves

TYPES
OF…

HEATWAVE

1 Dry heatwaves © Thinkstock Heatwaves
Occurring in continental or If you can’t stand the heat… the Met Office
Mediterranean regions, dry suggests you stay indoors
heatwaves are linked to clear
skies and high solar radiation, Although, according to Met Office meteorologist John “Temperatures have exceeded 30ºC in the UK,” he explains, “[but
as well as windy conditions, Hammond, there’s no official definition of a heatwave, around] Europe and the world, weather conditions can bring
which can increase stress at these hot-weather phenomena take their toll not only temperatures exceeding 40ºC. This has happened in
excessive heat levels. on a population’s health, but also business and infrastructure – Mediterranean regions, the Middle East and Australia among
such as power, water and transport. A heatwave is a period other areas.”
2Moist heatwaves of unusually hot or humid weather that lasts at least two or
Moist heatwaves bring hot three days – and remaining hot throughout the nights – that Heatwaves are relative to an area’s climate – temperatures that
and humid conditions during affects large areas. Heatwaves are caused by a system of would constitute a heatwave in one area might not in another
the day with nighttime cloud higher atmospheric pressure, whereby air from upper levels location – and the health effects on the individual are also relative
that prevents heat from of the atmosphere descends and rotates out. As it descends, to a range of risk factors. People adapt and become accustomed to
escaping. These muggy it compresses, increasing the temperature. The outward their long-term temperature patterns, making a heatwave a
heatwaves are mostly found in flow, meanwhile, makes it difficult for other systems to enter relative experience.
mid-latitude temperate and the area, and the large size and slow speed of the hot air
maritime regions. causes the heatwave to remain for days or even weeks. The The Met Office Heat Health Watch is a warning system that
lack of clouds means that an affected area is struck with issues alerts – levels 1-4 – if a heatwave is imminent. “[We] can
3Heat island effect strong sunlight. identify weather patterns that might bring hot temperatures to
Large urban areas can Hammond reveals that the hottest temperatures in the UK are the UK several days in advance,” explains Hammond. “When
experience a kind of likely to be over parts of central and southern England, away from high temperatures are expected, detailed advice will go to the
microclimate known as the heat immediate coastal areas, which are cooled by sea breezes. relevant health organisations, so they can inform people affected
island effect. Here, conditions by the heat. Met Office forecasts on TV, radio, newspapers and
during a heatwave tend to be online will also provide temperature forecasts for the public.”
worse because the Sun’s heat is
stored in the tarmac of roads
and cement of buildings and is
unable to escape until the night.

TEMP 20oC 68oF 25oC 77oF 30oC 86oF

Effects on State: State: State:
the body
Normal Still normal Mildly
How rising uncomfortable
temperatures can Heart rate normal, Heart rate normal, body
affect your body Moderate sweating keeps body cool
body comfortable sweats slightly
when it evaporates from our skin,

but concentration is reduced

048

5 TOP Power outage Hyperthermia Hottest recorded temp Sunny side up Meltdown
FACTS
1 Heatwaves threaten resources 2 Unlike hypothermia (core 3 John Hammond informed 4 The Met Office records show 5 Roads melted in England in
HEATWAVES due to increased water and temperature drop), us that the highest recorded that in terms of average July 2006 when temperatures
electricity consumption. For hyperthermia is a condition temperature in the world annual sunshine, the sunniest reached 37˚C (official
example, power outages have caused by heat stroke was a whopping 58˚C in place on the planet is Yuma, heatwave conditions as the
been known to occur due to whereby you absorb more Libya back on 13 September Arizona, which enjoys 4,300 average max temp for that
increased use of air conditioning. heat than can dissipate. 1922. Scorchio! hours each year. week is usually 21-23˚C).

DID YOU KNOW? In the UK’s heatwave of 1967, penguins from Chessington Zoo went to the local ice rink to cool off

Australia heatwave Interview
breaks records
The Met Office’s
This map of Australia captured by NASA’s Moderate-Resolution Imaging Spectroradiometer (MODIS) compares Patrick Sachon,
January-February 2009’s average land temperature with previous years. Red areas are warmer than previously Health Service
while blue areas are cooler. The darker the colour the more extreme the temperature change. Really dark red or Development
dark blue areas reveal where the difference in temperature is 10ºC higher or lower than previously. Manager gives
his advice on
The abnormally hot temperatures here – the highest recorded being 48.8°C in Hopetoun, Victoria – indicate a heat health
severe heatwave. Slow-moving high pressure lingered over the Tasman Sea and conditions conspired to cause
hot tropical air to blow across south-east Australia. The extreme heat worsened the country’s already- At what temperature does the body begin to notice
dangerous bushfire season, and led to the Black Saturday bushfires, which caused the deaths of 173 people on negative effects from heat?
Saturday 7 February, also destroying homes and towns in the process. The effects of heat on people’s health in the UK starts at
relatively modest temperatures. Epidemiological studies have
South-east Australia’s January heatwave set the record for Melbourne’s highest recorded temperature of a shown that maximum air temperatures of only 23-24˚C are
blistering 46.4ºC according to the Bureau of Meteorology in Melbourne. associated with excess summer mortality.

The north The south © NASA Physiologically, when the ambient temperature is higher
than the skin temperature, the body has to regulate its
While the south of the country sweltered, some Melbourne had the temperature by losing heat through sweating. At this stage if
northern areas experienced cooler than normal greatest temperature any other factor reduces the body’s effectiveness of sweating
temperatures – perhaps due to above-average change compared – such as dehydration, close fitting clothing or taking certain
rainfall during the rainy season. with normal. medications – it can cause the body to overheat.
Acclimatisation and adaptation play an important part in how
well people can tolerate different levels of heat. This is why
people in somewhere like Madrid are more accustomed to
higher temperatures than people in London.

What is the highest temperature a human body can
tolerate?
There are currently no studies that we are aware of that have
identified a maximum temperature [the body can tolerate]. As I
say, acclimatisation and adaptation have an important part to
play in how well people can tolerate different levels of heat. In
England, relatively modest maximum temperatures are
associated with excess mortality.

Why does heat make us dehydrated?
In order to lose heat we need to sweat, this leads to fluid loss. If
we do not replace this fluid we can become dehydrated. One of
the most important things to do in hot weather is to drink
sufficient fluids, such as water or fruit juices.

How do people living in much hotter countries than the
UK cope with/grow accustomed to excessive the heat in
the long term?
Their bodies are more acclimatised to the heat and their way of
living – the clothes they wear, the houses they live in and the
way they live their lives – are more adapted to hot weather.

35oC 95oF 40oC 104oF 45oC 113oF

State: State: State: Learn more

Heat Heat Heat For expert advice on coping in a
cramp exhaustion stroke heatwave, visit www.nhs.uk.
The Met Office at www.
Heart rate and sweating Heart rate becomes rapid, the Core temperature raised, sweating metoffice.gov.uk is also a great
resource for weather-based news
increase, body loses water and salts body feels tired and nauseous and stops, skin becomes dry. Fainting, and information.

causing muscles to ache sweating becomes heavier organ damage and death possible 049

DEADLY WEATHER

Superstorms

Rise of the

Superstorm

The science behind tornadoes with the power to devastate cities

Every year around 1,200 tornadoes near-total devastation, levelling multistorey On 20 May 2013, severe weather warnings
touch down in the USA. Most occur in a buildings, tearing homes from their very were issued for Oklahoma; a polar jet stream
region nicknamed Tornado Alley, with foundations and lifting asphalt from the roads. came over the Rockies into the southern Great
Texas, Oklahoma and Kansas at its core. Plains, and simultaneously a low-pressure
The most destructive of 2013 was the Moore North America has unique geography, which system moved over the Upper Midwest region.
Tornado, which touched down at 2.56pm CDT on provides a deadly spawning ground for storms Differences in wind speed at different altitudes
20 May, near Newcastle, OK. It was on the and tornadoes. The Rocky Mountains extend – known as wind shear – caused the air to spin,
ground for 40 minutes and drew a 27-kilometre from north to south along the west side of the circulating in a horizontal vortex, and in
(17-mile) path through the state, 2.1 kilometres continent. As wind travels over the Rockies, it combination with moisture and atmospheric
(1.3 miles) across at its widest point. Wind becomes cold and loses moisture via rain and instability. At 2pm CDT, this led to the
speeds were in excess of 322 kilometres (200 snow, producing cool, dry air at high altitudes. development of a thunderstorm containing
miles) per hour, placing the tornado in the When this air hits warm, humid air from the persistent, rotating mesocyclones.
highest category on the Enhanced Fujita (EF) Gulf of Mexico water vapour condenses and
Scale: EF5. Tornadoes of this class cause forms storm clouds. This releases huge amounts Mesocyclones powerful enough to generate
of energy, causing atmospheric instability. tornadoes often result in hailstorms.

050